Biosynthesis of riboflavin: characterization of the bifunctional deaminase-reductase of Escherichia coli and Bacillus subtilis.

AUTOR(ES)

Richter, G

RESUMO

The ribG gene at the 5' end of the riboflavin operon of Bacillus subtilis and a reading frame at 442 kb on the Escherichia coli chromosome (subsequently designated ribD) show similarity with deoxycytidylate deaminase and with the RIB7 gene of Saccharomyces cerevisiae. The ribG gene of B. subtilis and the ribD gene of E. coli were expressed in recombinant E. coli strains and were shown to code for bifunctional proteins catalyzing the second and third steps in the biosynthesis of riboflavin, i.e., the deamination of 2,5-diamino-6-ribosylamino-4(3H)-pyrimidinone 5'-phosphate (deaminase) and the subsequent reduction of the ribosyl side chain (reductase). The recombinant proteins specified by the ribD gene of E. coli and the ribG gene of B. subtilis were purified to homogeneity. NADH as well as NADPH can be used as a cosubstrate for the reductase of both microorganisms under study. Expression of the N-terminal or C-terminal part of the RibG protein yielded proteins with deaminase or reductase activity, respectively; however, the truncated proteins were rather unstable.

Documentos Relacionados

• Presence of Escherichia coli of a deaminase and a reductase involved in biosynthesis of riboflavin.
• Biosynthesis of Bacillus licheniformis penicillinase in Escherichia coli and in Bacillus subtilis.
• Biosynthesis of riboflavin: cloning, sequencing, mapping, and expression of the gene coding for GTP cyclohydrolase II in Escherichia coli.
• Biosynthesis of riboflavin: an unusual riboflavin synthase of Methanobacterium thermoautotrophicum.
• Accumulation of enoxacin by Escherichia coli and Bacillus subtilis.