Microbiology, Vol 145, 1595-1604, Copyright © 1999 by Society for General Microbiology
Ribonucleotide reductase (RNR) of Corynebacterium glutamicum ATCC 13032 -- genetic characterization of a second class IV enzyme
W Oehlmann and G Auling
Institut fur Mikrobiologie, Universitat Hannover, Schneiderberg 50, D-30167 Hannover, Germany
Ribonucleotide reductases (RNRs) encoded by nrd (nucleotide reduction)
genes are unique enzymes providing the DNA precursors in all living
organisms and several viruses. The designation of four classes of RNRs
reflects their use of diverse metallo-cofactors. Using oligonucleotide
primers derived from conserved domains of the primary structure of known
NrdA and NrdE proteins, an internal 938 bp fragment of the nrdE gene was
amplified from genomic DNA of Corynebacterium glutamicum. With this PCR
product a 4.36 kb fragment was identified and cloned containing the nrdHIE
genes of C. glutamicum. A probe derived from nrdF2 of Mycobacterium
tuberculosis allowed the cloning and sequencing of the nrdF gene located
3.1 kb further downstream, encoding the small subunit of the C. glutamicum
RNR. Conjugative introduction of nrdE from C. glutamicum complemented
thermosensitive mutants of Corynebacterium ammoniagenes which had a
defective catalytic subunit of the Mn-RNR. The authors provide arguments
for allocation of the C. glutamicum NrdEF proteins to class IV in the RNR
classification scheme of Stubbe & van der Donk (1995) [Chem Biol 2,
793--801].
