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1 Department of Microbiology, The University of Mississippi Medical Center, Jackson, 2500 North State Street, MS 39216-4505, USA
2 Department of Biochemistry, The University of Mississippi Medical Center, Jackson, 2500 North State Street, MS 39216-4505, USA
Correspondence
Michael D. Lundrigan
mlundrigan{at}microbio.umsmed.edu
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ABSTRACT |
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-D-maltoside; DMNQ, dimethylnaphthoquinone; DMNQH2, dimethylnaphthoquinol; TMPD, N,N,N',N'-tetramethyl-p-phenylenediamine
Present address: Center for Infectious Disease and Vaccinology, The Biodesign Institute, Arizona State University, PO Box 875401, Tempe, AZ 85287, USA.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
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). This potential is utilized by the ATP synthase to produce ATP. The respiratory electron-transfer chain can be divided in two: a quinone-reducing and a quinol-oxidizing side (Thony-Meyer, 1997; Hosler & Shapleigh, 2002). Electrons are transferred from cytoplasmic electron carriers (e.g. NADH2) to membrane-bound reductases (e.g. NADH-dehydrogenase), which in turn reduce quinone. The quinol then passes electrons in two possible directions, directly to a quinol-O2 oxidoreductase, or through the cytochrome c pathway. The latter consists of a quinol-cytochrome c oxidoreductase (the cytochrome bc1 complex) and a cytochrome c oxidase (terminal oxidase). Thus, the two ways terminal oxidases accept electrons are directly from quinol or from cytochrome c.
The wide variety of bacterial terminal oxidases fall into two groups based upon the structure of their active sites. The active sites of the haem-copper family contain a five-coordinate haem and a type 2 copper, while the active sites of the bd-type oxidases are composed of two closely associated haems. Some haem-Cu oxidases oxidize cytochrome c, others quinol, and all are proton pumps. The bd-type oxidases all oxidize quinol and do not function as proton pumps, but these enzymes do have a high affinity for O2 (D'Mello et al., 1996). Regardless of proton pumping, all terminal oxidases function as energy-transducing devices by consuming the protons for water production only from the inner surface of the membrane. Many bacteria synthesize one or more cytochrome c pathways plus a bd-type quinol oxidase. The Mycobacterium tuberculosis and Mycobacterium smegmatis genomes encode genes for two terminal oxidases, a bd-type quinol oxidase and a haem-Cu-type cytochrome c oxidase (Cole et al., 1998; Kana et al., 2001; http://www.tigr.org). The presence of a second bd-type oxidase has been proposed for M. smegmatis based on gene sequence homologies (Matsoso et al., 2005).
In mitochondria, soluble cytochrome c is reduced by cytochrome c1 of the bc1 complex and oxidized by the CuA centre in subunit II of an aa3-type cytochrome c oxidase. Eubacterial cytochrome c oxidases have evolved a variety of cytochrome c–cytochrome c oxidase interactions, at least partly in response to constraints imposed by different cell architectures. Gram-negative bacteria contain a periplasmic space analogous to the intermembrane space of mitochondria. Correspondingly, the mitochondrial-like cytochrome c oxidases of many 
-proteobacteria, including Rhodobacter sphaeroides and Paracoccus denitrificans, interact with soluble c-type cytochromes with homology to mitochondrial cytochrome c (Hosler et al., 1992; Castresana et al., 1994; Maneg et al., 2004). However, these oxidases also interact reversibly with a membrane-anchored cytochrome c, also related to mitochondrial cytochrome c (Hosler et al., 1992; Daldal et al., 2001; Maneg et al., 2004). Gram-positive bacteria do not possess a periplasmic space or an outer membrane; thus the cytochrome c-binding surface of the oxidase is topologically outside the cell. In apparent response to this, Bacillus subtilus synthesizes a caa3-type cytochrome c oxidase in which a cytochrome c domain is fused to the extramembrane portion of subunit II of the enzyme complex (Bengtsson et al., 1999). The acid-fast bacteria, including Mycobacterium spp., have structural similarities to both Gram-positive and Gram-negative bacteria. The genomes of the Corynebacterium, Mycobacterium and Rhodococcus species examined encode neither soluble cytochrome c nor an independent membrane-bound cytochrome c (Niebisch & Bott, 2001; Sakamoto et al., 2001; Sone et al., 2003). Analysis of the Corynebacterium glutamicum genes encoding its bc1 complex and its haem-Cu-type oxidase revealed two modified components (Sakamoto et al., 2001). The qcrC gene of the bc1 complex encodes an extra region predicted to lie in the extramembrane domain that includes a binding site for a second haem c. This cytochrome c1 can be considered as a fusion between two cytochrome c proteins (Sone et al., 2001). The gene for subunit II of the oxidase encodes an additional 30 amino acids containing many charged residues. The hypothesis was put forth that these enlarged domains mediate an interaction between the bcc complex and the terminal oxidase that precludes the necessity for an independent cytochrome c. This has been verified in C. glutamicum by activity assays and the co-isolation of the bcc complex and an aa3-type cytochrome oxidase complex (Niebisch & Bott, 2003). As shown by Sakamoto et al. (2001), the genes for the bc1 complex and the haem-Cu oxidase of mycobacteria are very similar to those of corynebacteria, suggesting a similar scenario.
Here, we have analysed isolated cytoplasmic membranes of M. smegmatis and found that a detergent-resistant association of the predicted bcc complex and an aa3-type oxidase constitutes the cytochrome c-dependent pathway of the respiratory chain. The results demonstrate that hydrophobic interactions provide the primary interactive force between the bcc and aa3 complexes while ionic interactions may play a role in aligning the two complexes for efficient electron transfer.
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METHODS |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
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). M. smegmatis LR222 (Beggs et al., 1995) and derivatives were routinely cultured in tryptic soy broth (Difco) containing 0·5 % Tween 80 at 37 °C.
Membrane isolation.
This followed the procedure of Lee et al. (1992). Briefly, harvested M. smegmatis cells were suspended in 50 mM KH2PO4, pH 7·2, 1 mM EDTA and 1 mM phenylmethanesulfonyl fluoride (Sigma). Cell lysis was achieved by three passes through a French pressure cell at 4 °C and 16 000 p.s.i. (110·4 MPa). The lysate was centrifuged at 3000 g for 15 min to remove cell debris. The resulting supernatant was centrifuged at 100 000 g for 1 h to pellet the membrane fraction, washed in 50 mM KH2PO4, pH 7·2, 1 mM EDTA, and repelleted. The resulting membranes were used in spectral studies and activity measurements.
Difference spectra.
To determine the cytochrome aa3 content, membranes were dissolved in 3 % dodecyl -D-maltoside (DM; Anatrace) in 50 mM KH2PO4, pH 7·2, 1 mM EDTA and dithionite-reduced minus ferricyanide-oxidized spectra (
605–630=24 mM–1 cm–1) were recorded at room temperature using a Hitachi U-3000 UV-visible spectrophotometer (Hiser et al., 2000).
Activity assays.
Rates of oxygen consumption were determined using a Clark-type oxygen electrode in a magnetically stirred chamber at 25 °C in 50 mM KH2PO4, pH 6·5, 1 mM EDTA. Isolated membranes containing 21·5 pmol cytochrome aa3 were added to each reaction. Quinol-driven O2 reduction activity was determined by using dimethylnaphthoquinol (DMNQH2) as the electron donor. DMNQH2 was generated in the reaction using DT-diaphorase (generously provided by Dr Gary Cecchini of UCSF) to mediate the reduction of 2,3-dimethyl 1,4-naphthoquinone (DMNQ, 0·3 mM; also from Dr Cecchini) by NADH2; each reaction was initiated by the addition of 0·2 mM NADH2. Cytochrome c oxidase activity was determined using 0·7 mM tetramethyl-p-phenylenediamine (TMPD) plus 3 mM sodium ascorbate as electron donors. The addition of detergent, salts, or inhibitors to any reaction preceded the addition of the electron donor.
Genetic and molecular manipulations.
All cloning and DNA manipulations followed standard molecular techniques (Sambrook et al., 1989). M. smegmatis sequence data were obtained from The Institute for Genomic Research (TIGR) through the website at http://www.tigr.org. The wild-type bd-type oxidase gene cluster was obtained by PCR from M. smegmatis LR222 genomic DNA. PCR was carried out using pfuTurbo polymerase (Stratagene) in a Bio-Rad Gene Cycler. The oligonucleotide primers (supplied by Invitrogen Life Technologies) were: 5'-ATCGTGGTGGGCGTGTGGCTCAT-3' (forward) and 5'-CGGGTCGGCGGGGGTGTCT-3' (reverse). PCR products were isolated from agarose and cloned into pCR4Blunt-TOPO (Invitrogen Life Technologies), forming pCR4SMbd. Constructs were verified as correct by sequencing the ends of the cloned DNA using sequencing primers for pCR4Blunt-TOPO. Electroporation of M. smegmatis LR222 followed the procedure of Zhu et al. (1998).
Creation of a cytochrome bd deletion strain.
A 1610 bp EcoRI–SmaII fragment, containing a portion of the genes for subunits I and II of the bd-type oxidase, was cloned from pCR4SMbd into pUC18 (Invitrogen), forming pUCSMbd. The kanamycin-resistance cassette from Tn903 on a BamHI fragment was cloned into a BamHI site, thus disrupting the gene for subunit I of the bd-type oxidase. The resulting construct, pUCSMbdKan, was digested with EcoRI and the linear fragment carrying the mutant allele was electroporated into LR222. Mutants were selected on plates containing 15 µg kanamycin ml–1 and were confirmed by PCR of genomic DNA using primers lying outside the mutated gene region and difference spectra of membrane extracts. The oligonucleotide primers used for mutagenesis verification were: 5'-ATCGTGGTGGGCGTGTGGCTCAT-3' (forward) and 5'-TCAGTGGTGGTGGTGGTGGTGGCTCGACCGCCTGGACAA-3' (reverse). One mutant strain, named JAM1, was chosen for further study.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMETHODSRESULTSDISCUSSIONREFERENCES |
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630 nm) containing haems B and D plus a cytochrome c oxidase containing haem A (600 nm) (Fig. 1b and Kana et al., 2001). The presence of these two oxidases predicts that the respiratory chain of M. smegmatis is branched at the level of menaquinol, which can pass its electrons to either the bd oxidase or a cytochrome c branch composed of the bcc complex and an aa3-type oxidase. In order to characterize the cytochrome c branch of the respiratory chain, a strain deleted in the bd-type oxidase was created (see Methods). Verification that the bd-type oxidase was absent from this strain, called JAM1, was obtained in three ways. First, the genomic copy of the gene for subunit I of the bd-type oxidase that is interrupted by the kanamycin-resistance cassette should be approximately 1 kb larger than the wild-type gene. PCR was performed on genomic DNA from JAM1 and wild-type M. smegmatis using primers that would hybridize outside the mutated gene region. Agarose gel electrophoresis revealed a 1 kb difference between JAM1 and the wild-type PCR products (Fig. 1a), indicating that the gene for subunit I was interrupted. Second, the 630 nm signal indicative of the bd-type oxidase is absent in membranes isolated from JAM1 (Fig. 1b). Third, the cyanide sensitivity of the O2 reduction activity catalysed by isolated membranes was significantly altered in JAM1. Typically, a haem-Cu cytochrome c oxidase is more sensitive to cyanide than bd-type oxidases (Junemann, 1997; Thony-Meyer, 1997). Fig. 2 shows that the O2 reduction activity catalysed by JAM1 membranes lacking the bd-type oxidase is considerably more sensitive to cyanide than wild-type membranes containing both the aa3-type and the bd-type oxidases. The data are consistent with apparent Ki values of 1 µM and 1 mM, as previously observed for the aa3-type and bd-type oxidases of C. glutamicum, respectively (Sone, 1990; Kusumoto et al., 2000).
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). An NADH-dehydrogenase reduces the menaquinone pool (Thony-Meyer, 1997; Hosler & Shapleigh, 2002). The addition of the detergent DM to a final concentration of 16 mg (mg total protein)–1 was sufficient to completely abolish this NADH-dependent activity by dissolving the membrane and dispersing the electron-transfer complexes (Fig. 3a). Addition of the exogenous quinol DMNQH2 restored O2 reduction activity to dissolved membranes originally isolated from both wild-type M. smegmatis and JAM1 (Fig. 3b). In the wild-type membranes, the bd-type oxidase can oxidize DMNQH2 and reduce O2. However, the presence of quinol-driven O2 reduction in solubilized JAM1 membranes indicates a detergent-resistant association of the cytochrome bcc and aa3 complexes since only the former can oxidize quinol and only the latter can reduce O2.
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If the quinol-driven activity exhibited by detergent-solubilized JAM1 membranes is due to a detergent-resistant association of the cytochrome bcc and aa3 complexes, then cytochrome bc1 complex inhibitors should prevent O2 reduction. Fig. 4 shows this to be the case. The addition of micromolar amounts of antimycin A and myxothiazol, well-established inhibitors of the cytochrome bc1 complex (Gao et al., 2003), totally abolished quinol-driven O2 reduction by dissolved JAM1 membranes. The quinol-driven O2 reduction activity of dissolved wild-type membranes in the presence of antimycin A and myxothiazol is attributed to the bd-type oxidase since these inhibitors do affect bd-type oxidases but to a lesser degree (Bertsova et al., 1997).
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; Assempour et al., 1998; Maneg et al., 2004). The activity of the cytochrome c oxidase can be measured independently by reducing the c-type cytochromes with ascorbate plus the mildly hydrophobic one-electron donor TMPD (Drachev et al., 1976; Jurtshuk et al., 1981). Neither the addition of soluble horse heart cytochrome c (Fig. 5) nor soluble cytochrome c2 of R. sphaeroides (data not shown) increased the rate of ascorbate/TMPD-driven O2 reduction to a rate greater than that supported by ascorbate/TMPD alone (Fig. 5). This suggests an inability of soluble cytochrome c to access its binding site on subunit II of the oxidase.
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). To test whether or not the charged residues participate in ionic interactions required for the association of the cytochrome bcc and aa3 complexes, the effect of monovalent and divalent salts on the quinol-driven O2 reduction activity of JAM1 membranes was assessed (Fig. 6). Interestingly, high concentrations of monovalent salts had no inhibitory effect on quinol-driven O2 reduction activity, indicating that disruption of any putative ionic interactions is not sufficient to dissociate the bcc complex from the aa3-type oxidase. However, the addition of divalent cations, as 0·5 M MgCl2 or MnSO4, essentially abolished DMNQH2-supported O2 reduction (Fig. 6). The inhibitory effects of MgCl2 were enhanced when the detergent concentration was simultaneously increased. In Fig. 7 the effect of 16 and 160 mg DM (mg total protein)–1 in the presence of a monovalent and a divalent salt on quinol oxidase activity is compared. While the detergent had no increased inhibitory effect in combination with 1 M KCl, 160 mg DM (mg protein)–1 along with 0·1 M MgCl2 inhibited O2 reduction by about 59 % as compared to the rate in the absence of salt at this detergent concentration. An explanation for the effect of divalent salts is presented below.
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DISCUSSION |
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). The work presented here provides the biochemical evidence for this proposal. The gene sequence of cytochrome c1 of the M. smegmatis bc1 complex indicates the presence of a second cytochrome c, as previously seen for C. glutamicum and Rhodococcus rhodochrous (Niebisch & Bott, 2001; Sakamoto et al., 2001; Sone et al., 2003). Analysis of the complete M. tuberculosis genome and the partial genome of M. smegmatis indicates the absence of any independent membrane-bound or soluble cytochromes c in these species, as in other acid-fast bacteria (Niebisch & Bott, 2001; Sakamoto et al., 2001; Sone et al., 2003). Therefore, the likely candidate for the cytochrome c that interacts with the aa3-type oxidase is this second haem C of cytochrome c1 of the M. smegmatis bcc complex. Our results provide strong evidence for the functional association of the cytochrome bcc complex and the aa3-type cytochrome c oxidase of M. smegmatis. First, exogenous quinol supports O2 reduction activity in the presence of detergent concentrations sufficient to solubilize the membrane. This is similar to the quinol oxidase activity of the isolated cytochrome bcc–aa3 complex of C. glutamicum. Confirmation that the quinol is being oxidized by the bcc complex, and not by an unusual reaction of the aa3-type terminal oxidase, is shown by our finding that known inhibitors of the bc1 complex inhibit quinol-driven O2 reduction. Together, these results indicate direct electron transfer between the two complexes of the cytochrome c pathway.
The data of Fig. 3(b)
may be interpreted as disruption of the cytochrome bcc–aa3 interaction by high concentrations of detergent. However, ascorbate/TMPD-driven O2 reduction activity was not inhibited by the same high levels of detergent (Fig. 5). Significant TMPD oxidation generally requires the association of a cytochrome c with the oxidase. For example, at the concentration of TMPD used, the mitochondrial aa3-type oxidase exhibits a turnover number of less than 2 s–1 (Crinson & Nicholls, 1992). The purified aa3-type oxidase of C. glutamicum, which contains no cytochrome c, oxidizes TMPD at the slow rate of <1 s–1 (Sakamoto et al., 2001). Thus, the retention of higher rates of TMPD oxidation at high detergent concentrations (Fig. 5) suggests a continued association of cytochrome c1 with the oxidase. The inhibition of quinol-driven O2 reduction by high detergent concentrations, then, could be due partly to the separation of the cytochrome bcc–aa3 complexes and partly to disruption of the cytochrome bcc complex, leaving cytochrome c1 associated with the aa3-type oxidase.
Unlike the prototype aa3-type oxidases of Rhodobacter sphaeroides and P. denitrificans (Hosler et al., 1992; Witt et al., 1998), the addition of soluble cytochrome c fails to stimulate the activity of the aa3-type oxidase of M. smegmatis, suggesting that the soluble cytochrome c cannot bind at the electron-transfer site on subunit II. Even so, of the four carboxylate residues that mediate the interaction of soluble cytochrome c with subunit II of cytochrome c oxidase in mitochondria and in R. sphaeroides, three are conserved in M. smegmatis cytochrome aa3 (Wang et al., 1999; Zhen et al., 1999). A conserved tryptophan has been shown to mediate electron transfer between the haem edge of cytochrome c and CuA in subunit II (Wang et al., 1999). This tryptophan and surrounding residues are present in the aa3-type oxidase of M. smegmatis. Conservation of the electron-transfer interface on subunit II suggests that the geometry of the productive interaction between the second cytochrome c of the bcc complex with its binding site on the aa3-type oxidase is likely to be similar to that between soluble cytochrome c and mitochondrial-like cytochrome oxidases. A tight association of the cytochrome bcc complex with the aa3-type oxidase could prevent the binding of exogenous cytochrome c. However, the homologous aa3-type oxidase of C. glutamicum, in a preparation in which the cytochrome bcc complex is absent, also fails to oxidize soluble horse heart or yeast cytochrome c (Sakamoto et al., 2001). Thus, it seems more likely that additional residues predicted to be present in the extramembrane domain of subunit II, as compared to the mitochondrial-like aa3-type oxidases, interfere with the binding of soluble cytochrome c. Interestingly, Weinstein et al. (2005) state that the aa3-type oxidase of M. tuberculosis readily oxidizes bovine and yeast soluble cytochrome c; actual rates were not reported. The genomic evidence suggests that the cytochrome bcc–aa3 interaction in M. tuberculosis should be very similar to that of M. smegmatis and C. glutamicum.
We have probed the forces that mediate the interaction between the cytochrome bcc and aa3 complexes using both detergent and monovalent and divalent salts. Monovalent salts disrupt the association of soluble cytochrome c with the mitochondrial-like cytochrome c oxidase (Hosler et al., 1992; Witt et al., 1998), but the association of the bcc complex with the aa3-type oxidase is resistant to KCl or NaCl. This argues against ionic interactions being primarily responsible for the cytochrome bcc–aa3 interaction, as originally suggested for the C. glutamicum system on the basis of the high number of charged residues present in the additional string of residues in subunit II of the oxidase (Sakamoto et al., 2001). The aa3-type oxidase of R. sphaeroides also interacts efficiently with a membrane-bound cytochrome c that mediates between the bc1 complex and the oxidase (Hosler et al., 1992; Daldal et al., 2001). This cytochrome c–cytochrome oxidase interaction is easily disrupted by low levels of detergent, while the cytochrome bcc–aa3 interaction in M. smegmatis membranes is not. Thus, the conclusion can be drawn that the association of the cytochrome bcc–aa3 complexes depends largely upon hydrophobic interactions.
Results obtained by modifying ionic strength with monovalent salt do not exclude a role for ionic interactions in an association of the cytochrome bcc and aa3 complexes that promotes optimal electron transfer. Divalent cations are capable of bridging negatively charged residues. Distortion of the electron-transfer interface between the second C haem of the cytochrome bcc complex and CuA in subunit II of the cytochrome aa3 complex seems the likely explanation for the strong inhibition of quinol-driven O2 reduction by Mg2+ and Mn2+. Interestingly, this effect would not be evident in studies of the interaction of soluble cytochromes c with cytochrome oxidase since the ionic strength of the divalent salts would prevent the initial binding. The presence of divalent cations leads to further inhibition by high detergent concentrations, as would be expected if detergent loosens the cytochrome bcc–aa3 interaction while divalent cations distort the cytochrome c1–subunit II interface.
Groups working on the cytochrome bcc–aa3 interaction in C. glutamicum have worked to provide evidence for this interaction through protein purification. In one case, only the aa3-type oxdase was purified (Sakamoto et al., 2001). Using lower detergent concentrations, Niebisch & Bott (2003) were able to purify a complex with quinol-driven O2 reduction activity from C. glutamicum membranes. The isolated bcc–aa3 complex, however, was partially dissociated. Our attempts to isolate a cytochrome bcc–aa3 complex from M. smegmatis by lithium dodecyl sulfate (LDS) gel electrophoresis were not successful. It may be that delipidation of the cytochrome bcc and aa3 complexes by all of these procedures destabilize the bcc–aa3 interaction.
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ACKNOWLEDGEMENTS |
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REFERENCES |
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Beggs, M. L., Crawford, J. T. & Eisenach, K. D. (1995). Isolation and sequencing of the replication region of Mycobacterium avium plasmid pLR7. J Bacteriol 177, 4836–4840.
Bengtsson, J., Tjalsma, H., Rivolta, C. & Hederstedt, L. (1999). Subunit II of Bacillus subtilis cytochrome c oxidase is a lipoprotein. J Bacteriol 181, 685–688.
Bertsova, Y. V., Bogachev, A. V. & Skulachev, V. P. (1997). Generation of protonic potential by the bd-type quinol oxidase of Azotobacter vinelandii. FEBS Lett 414, 369–372.[CrossRef][Medline]
Castresana, J., Lubben, M., Saraste, M. & Heggins, D. G. (1994). Evolution of cytochrome oxidase, an enzyme older than atmospheric oxygen. EMBO J 13, 2516–2525.[Medline]
Cole, S. T., Brosch, R., Parkhill, J. & 39 other authors (1998). Decifering the biology of Mycobacterium tuberculosis from the complete genome sequence. Nature 393, 537–544.[CrossRef][Medline]
Crinson, M. & Nicholls, P. (1992). Routes of electron transfer in beef heart cytochrome c oxidase: is there a unique pathway used by all reductants? Biochem Cell Biol 70, 301–308.[Medline]
Daldal, F., Mandaci, S., Winterstein, C., Myllykallio, H., Cuyck, K. & Zannoni, D. (2001). Mobile cytochrome c2 and membrane-anchored cytochrome cy are both efficient electron donors to the cbb3- and aa3-type cytochrome c oxidases during respiratory growth of Rhodobacter sphaeroides. J Biol Chem 183, 2013–2024.
De Bruijn, F. J. & Rossbach, S. (1994). Transposon mutagenesis. In Methods for General and Molecular Bacteriology, pp. 387–405. Edited by P. Gerhardt. Washington, DC: American Society for Microbiology.
D'Mello, R., Hill, S. & Poole, R. K. (1996). The cytochrome bd quinol oxidase in Escherichia coli has an extremely high oxygen affinity and two oxygen-binding haems: implications for regulation of activity in vivo by oxygen inhibition. Microbiology 142, 755–763.
Drachev, L. A., Jasaitis, A. A., Kaulen, A. D., Kondrashin, A. A., Chu, L. V., Semenov, A. Y., Severina, I. I. & Skulachev, V. P. (1976). Reconstitution of biological molecular generators of electric current. Cytochrome oxidase. J Biol Chem 251, 7072–7076.
Gao, X., Wen, X., Esser, L., Quinn, B., Yu, L., Yu, C. A. & Xia, D. (2003). Structural basis for the quinone reduction in the bc1 complex: a comparative analysis of crystal structures of mitochondrial cytochrome bc1 with bound substrate and inhibitors at the Qi site. Biochemistry 42, 9067–9080.[CrossRef][Medline]
Hiser, L., Valentin, M. D., Hamer, A. G. & Hosler, J. P. (2000). Cox11p is required for stable formation of the CuB and magnesium centers of cytochrome c oxidase. J Biol Chem 275, 619–623.
Hosler, J. P., Fetter, J., Tecklenburg, M. M. J., Espe, M., Lerma, C. & Ferguson-Miller, S. (1992). Cytochrome aa3 of Rhodobacter sphaeroides as a model for mitochondrial cytochrome c oxidase: purification, kinetics, proton pumping and spectral analysis. J Biol Chem 267, 24264–24272.
Hosler, J. P. & Shapleigh, J. P. (2002). Principles of aerobic respiration. In Encyclopedia of Environmental Microbiology, pp. 149–160. Edited by G. Bitton. New York: Wiley.
Junemann, S. (1997). Cytochrome bd terminal oxidase. Biochim Biophys Acta 1321, 107–127.[Medline]
Jurtshuk, P., Jr, Mueller, T. J. & Wong, T. Y. (1981). Isolation and purification of the cytochrome oxidase of Azotobacter vinelandii. Biochim Biophys Acta 637, 374–382.[Medline]
Kana, B. D., Weinstein, E. A., Avarbock, D., Dawes, S. S., Rubin, H. & Mizrahi, V. (2001). Characterization of the cydAB-encoded cytochrome bd oxidase from Mycobacterium smegmatis. J Bacteriol 183, 7076–7086.
Kusumoto, K., Sakiyama, M., Sakamoto, J., Noguchi, S. & Sone, N. (2000). Menaquinol oxidase activity and primary structure of cytochrome bd from the amino-acid fermenting bacterium Corynebacterium glutamicum. Arch Microbiol 173, 390–397.[CrossRef][Medline]
Lee, B.-Y., Hefta, S. A. & Brennan, P. J. (1992). Characterization of the major membrane protein of virulent Mycobacterium tuberculosis. Infect Immun 60, 2066–2074.
Maneg, O., Malatesta, F., Ludwig, B. & Drosou, V. (2004). Interaction of cytochrome c with cytochrome oxidase: two different docking scenarios. Biochim Biophys Acta 1655, 274–281.[Medline]
Matsoso, L. G., Kana, B. V., Crellin, P. K. & 7 other authors (2005). Function of the cytochrome bc1-aa3 branch of the respiratory network in mycobactera and network adaptation occurring in response to its disruption. J Bacteriol 187, 6300–6308.
Niebisch, A. & Bott, M. (2001). Molecular analysis of the cytochrome bc1-aa3 branch of the Corynebacterium glutamicum respiratory chain containing an unusual diheme cytochrome c1. Arch Microbiol 175, 282–294.[CrossRef][Medline]
Niebisch, A. & Bott, M. (2003). Purification of a cytochrome bc-aa3 supercomplex with quinol oxidase activity from Corynebacterium glutamicum. Identification of a fourth subunit of cytochrome aa3 oxidase and mutational analysis of diheme cytochrome c1. J Biol Chem 278, 4339–4346.
Sakamoto, J., Shibata, T., Mine, T., Miyahara, R., Torigoe, T., Noguchi, S., Matsushita, K. & Sone, N. (2001). Cytochrome c oxidase contains an extra charged amino acid cluster in a new type of respiratory chain in the amino-acid-producing Gram-positive bacterium Corynebacterium glutamicum. Microbiology 147, 2865–2871.
Sambrook, J., Fritsch, E. F. & Maniatis, T. (1989). Molecular Cloning: a Laboratory Manual, 2nd edn. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory.
Sone, N. (1990). Respiration-driven proton pumps. In The Bacteria, pp. 1–32. Edited by T. A. Krulwich. New York: Academic Press.
Sone, N., Nagata, K., Kojima, H., Tajima, J., Kodera, Y., Kanamaru, T., Noguchi, S. & Sakamoto, J. (2001). A novel hydrophobic diheme c-type cytochrome. Purification from Corynebacterium glutamicum and analysis of the QcrCBA operon encoding three subunit proteins of a putative cytochrome reductase complex. Biochim Biophys Acta 1503, 279–290.[Medline]
Sone, N., Fukuda, M., Katayama, S., Jyoudai, A., Syugyou, M., Noguchi, S. & Sakamoto, J. (2003). qcrCAB operon of a nocardia-form actinomycete Rhodococcus rhodochrous encodes cytochrome reductases complex with diheme cytochrome cc subunit. Biochim Biophys Acta 1557, 125–131.[Medline]
Thony-Meyer, L. (1997). Biogenesis of respiratory cytochromes in bacteria. Microbiol Mol Biol Rev 61, 337–376.[Abstract]
Wang, K., Zhen, Y., Sadoski, R., Grinnell, S., Geren, L., Ferguson-Miller, S., Durham, B. & Millett, F. (1999). Definition of the interaction domain for cytochrome c on cytochrome c oxidase. II. Rapid kinetic analysis of electron transfer from cytochrome c to Rhodobacter sphaeroides cytochrome oxidase surface mutants. J Biol Chem 274, 38042–38050.
Weinstein, E. A., Yano, T., Li, L.-S. & 7 other authors (2005). Inhibitors of type II NADH : menaquinone oxidoreductase represent a class of antitubercular drugs. Proc Natl Acad Sci U S A 102, 4548–4553.
Witt, H., Malatesta, F., Nicoletti, F., Brunori, M. & Ludwig, B. (1998). Cytochrome c binding site on cytochrome oxidase in Paracoccus denitrificans. Eur J Biochem 251, 367–373.[Medline]
Zhen, Y., Hoganson, C. W., Babcock, G. T. & Ferguson-Miller, S. (1999). Definition of the interaction domain for cytochrome c on cytochrome c oxidase. I. Biochemical, spectral, and kinetic characterization of surface mutants in subunit II of Rhodobacter sphaeroides cytochrome aa3. J Biol Chem 274, 38032–38041.
Zhu, W., Arceneaux, J. E. L., Beggs, M. L., Byers, B. R., Eisenach, K. D. & Lundrigan, M. D. (1998). Exochelin genes in Mycobacterium smegmatis: identification of an ABC transporter and two non-ribosomal peptide synthetase genes. Mol Microbiol 29, 629–639.[CrossRef][Medline]
Received 28 November 2005;
accepted 6 December 2005.
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| J MED MICROBIOL | ALL SGM JOURNALS | |
) and JAM1 (
). Membranes were mixed with increasing molar concentrations of KCN prior to the addition of NADH2. The results are expressed as the percentage of the initial rate when no cyanide was present.
