Harms E, Hsu J H, Subrahmanyam C S, Umbarger H E
J Bacteriol. 1985 Oct;164(1):207-16. doi: 10.1128/jb.164.1.207-216.1985.
The nucleotide sequence preceding the ilvGEDA operon has been examined and compared in five enteric organisms. The sequence in Escherichia coli B was identical to the earlier-described strain K-12 sequence. The sequences of Salmonella typhimurium and Klebsiella aerogenes were remarkably similar to that of E. coli and identical in that part of the leader region that specified the putative 32-amino-acid peptide. Thus, identical secondary structures could be postulated for the leaders of all three organisms, and regulation of operon expression could be like that postulated earlier for E. coli. Different secondary structures had to be postulated for the leader transcripts of Edwardsiella tarda and Serratia marcescens. Control of attenuation of the operon in these organisms by the level of leucyl tRNA could be explained only if ribosome stalling occurred at a single leucine codon. In both organisms, that single leucine codon is the rarely used CUA rather than the CUG that is in E. coli, S. typhimurium, and K. aerogenes.
已对五种肠道菌中ilvGEDA操纵子之前的核苷酸序列进行了检测和比较。大肠杆菌B中的序列与先前描述的K-12菌株序列相同。鼠伤寒沙门氏菌和气杆菌克雷伯氏菌的序列与大肠杆菌的序列非常相似，并且在指定假定的32个氨基酸肽段的前导区部分相同。因此，可以推测这三种菌的前导序列具有相同的二级结构，并且操纵子表达的调控可能与先前推测的大肠杆菌的情况类似。对于迟缓爱德华氏菌和粘质沙雷氏菌的前导转录本，必须推测出不同的二级结构。只有当核糖体在单个亮氨酸密码子处停滞时，才能解释这些菌中操纵子衰减受亮氨酰tRNA水平的控制。在这两种菌中，那个单个亮氨酸密码子是很少使用的CUA，而不是大肠杆菌、鼠伤寒沙门氏菌和气杆菌克雷伯氏菌中的CUG。
