FORMATE IS THE HYDROGEN DONOR FOR THE ANAEROBIC RIBONUCLEOTIDE REDUCTASE FROM ESCHERICHIA-COLI

Citation
E. Mulliez et al., FORMATE IS THE HYDROGEN DONOR FOR THE ANAEROBIC RIBONUCLEOTIDE REDUCTASE FROM ESCHERICHIA-COLI, Proceedings of the National Academy of Sciences of the United Statesof America, 92(19), 1995, pp. 8759-8762
Citations number
24
Categorie Soggetti
Multidisciplinary Sciences
ISSN journal
00278424
Volume
92
Issue
19
Year of publication
1995
Pages
8759 - 8762
Database
ISI
SICI code
0027-8424(1995)92:19<8759:FITHDF>2.0.ZU;2-1
Abstract
During anaerobic growth Escherichia coli uses a specific ribonucleosid e triphosphate reductase (class III enzyme) for the production of deox yribonucleoside triphosphates. In its active form, the enzyme contains an iron-sulfur center and an oxygen-sensitive glycyl radical (Gly-681 ). The radical is generated in the inactive protein from S-adenosylmet hionine by an auxiliary enzyme system present in E. coli. By modificat ion of the previous purification procedure, we now prepared a glycyl r adical-containing reductase, active in the absence of the auxiliary re ducing enzyme system. This reductase uses formate as hydrogen donor in the reaction. During catalysis, formate is stoichiometrically oxidize d to CO2, and isotope from [H-3] formate appears in water. Thus E. col i uses completely different hydrogen donors for the reduction of ribon ucleotides during anaerobic and aerobic growth. The aerobic class I re ductase employs redox-active thiols from thioredoxin or glutaredoxin t o this purpose. The present results strengthen speculations that class III enzymes arose early during the evolution of DNA.