Harder J, Follmann H, Hantke K
Fachbereich Chemie der Philipps-Universität, Marburg, Bundesrepublik Deutschland.
Z Naturforsch C J Biosci. 1989 Jul-Aug;44(7-8):715-8. doi: 10.1515/znc-1989-7-827.
An iron-sensitive mutant of E. coli with a Mudl phage insertion in the nrdB gene lacks subunit B2 of the key enzyme of DNA synthesis, ribonucleotide reductase. Nevertheless, these cells are capable of growing in minimal media under anaerobic conditions, indicating a second enzyme or pathway for deoxyribonucleotide synthesis. We here show that ribonucleotide reduction cannot be unambiguously measured in bacterial extracts whereas phosphorylase-catalyzed deoxyribosyl transfer does occur; however these salvage reactions could not function in vivo in the absence of deoxyribosides. It is suggested that the cells possess a specific, anaerobic ribonucleotide reductase which escapes detection under aerobic standard conditions, similar to the situation found in strictly anaerobic methanogens.
一种大肠杆菌铁敏感突变体，其nrdB基因中有Mudl噬菌体插入，缺乏DNA合成关键酶核糖核苷酸还原酶的B2亚基。然而，这些细胞能够在厌氧条件下的基本培养基中生长，这表明存在第二种脱氧核糖核苷酸合成酶或合成途径。我们在此表明，在细菌提取物中无法明确测定核糖核苷酸还原反应，而磷酸化酶催化的脱氧核糖基转移反应确实会发生；然而，在没有脱氧核苷的情况下，这些补救反应在体内无法发挥作用。有人提出，这些细胞拥有一种特定的厌氧核糖核苷酸还原酶，在有氧标准条件下无法检测到，这与严格厌氧的产甲烷菌的情况类似。
