HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Richard, D. J. Articles by Boxer, D. H. Search for Related Content PubMed PubMed Citation Articles by Richard, D. J. Articles by Boxer, D. H. Agricola Articles by Richard, D. J. Articles by Boxer, D. H.

Transcriptional regulation in response to oxygen and nitrate of the operons encoding the [NiFe] hydrogenases 1 and 2 of Escherichia coli

Department of Biochemistry, University of Dundee, Dundee DD1 4HN, Tayside, UK¹
Department of Molecular Microbiology, John Innes Centre, Norwich NR4 7UH, UK²
Centre for Metalloprotein Spectroscopy and Biology, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK³

Author for correspondence: Gary Sawers. Tel: +44 1603 456900 ext. 2750. Fax: +44 1603 454970. e-mail: gary.sawers{at}bbsrc.ac.uk

Synthesis of the [NiFe] hydrogenases 1 and 2 of Escherichia coli is induced in response to anaerobiosis and is repressed when nitrate is present in the growth medium. The hydrogenase 1 and hydrogenase 2 enzymes are encoded by the polycistronic hyaABCDEF and hybOABCDEFG operons, respectively. Primer extension analysis was used to determine the initiation site of transcription of both operons. This permitted the construction of single-copy lacZ operon fusions, which were used to examine the transcriptional regulation of the two operons. Expression of both was induced by anaerobiosis and repressed by nitrate, which is in complete accord with earlier biochemical studies. Anaerobic induction of the hyb operon was only partially dependent on the FNR protein and, surprisingly, was enhanced by an arcA mutation. This latter result indicated that ArcA suppresses anaerobic hyb expression and that a further factor, which remains to be identified, is involved in controlling anaerobic induction of operon expression. Nitrate repression of hyb expression was mediated by the NarL/NarX and NarP/NarQ two-component regulatory systems. Remarkably, a narP mutant lacked anaerobic induction of hyb expression, even in the absence of added nitrate. Anaerobic induction of hya expression was dependent on the ArcA and AppY regulators, which confirms earlier observations by other authors. Nitrate repression of the hya operon was mediated by both NarL and NarP. Taken together, these data indicate that although the hya and hyb operons share common regulators, there are important differences in the control of expression of the individual operons.

Keywords: anaerobic gene regulation, [NiFe] hydrogenases, Escherichia coli, nitrate regulation, transcription

This article has been cited by other articles:

				A. L. Zbell, S. L. Benoit, and R. J. Maier Differential expression of NiFe uptake-type hydrogenase genes in Salmonella enterica serovar Typhimurium Microbiology, October 1, 2007; 153(10): 3508 - 3516. [Abstract] [Full Text] [PDF]

				J. L. Rowe, G. L. Starnes, and P. T. Chivers Complex Transcriptional Control Links NikABCDE-Dependent Nickel Transport with Hydrogenase Expression in Escherichia coli J. Bacteriol., September 15, 2005; 187(18): 6317 - 6323. [Abstract] [Full Text] [PDF]

				A. T. Kovacs, G. Rakhely, D. F. Browning, A. Fulop, G. Maroti, S. J. W. Busby, and K. L. Kovacs An FNR-Type Regulator Controls the Anaerobic Expression of Hyn Hydrogenase in Thiocapsa roseopersicina J. Bacteriol., April 15, 2005; 187(8): 2618 - 2627. [Abstract] [Full Text] [PDF]

				Y. Kang, K. D. Weber, Y. Qiu, P. J. Kiley, and F. R. Blattner Genome-Wide Expression Analysis Indicates that FNR of Escherichia coli K-12 Regulates a Large Number of Genes of Unknown Function J. Bacteriol., February 1, 2005; 187(3): 1135 - 1160. [Abstract] [Full Text] [PDF]

				W. T. Self, A. Hasona, and K. T. Shanmugam Expression and Regulation of a Silent Operon, hyf, Coding for Hydrogenase 4 Isoenzyme in Escherichia coli J. Bacteriol., January 15, 2004; 186(2): 580 - 587. [Abstract] [Full Text] [PDF]

				S. Laska, F. Lottspeich, and A. Kletzin Membrane-bound hydrogenase and sulfur reductase of the hyperthermophilic and acidophilic archaeon Acidianus ambivalens Microbiology, September 1, 2003; 149(9): 2357 - 2371. [Abstract] [Full Text] [PDF]