The ilvB locus of Escherichia coli K-12 is an operon encoding both subunits of acetohydroxyacid synthase I.
The ilvB locus of Escherichia coli K-12 is an operon encoding both subunits of acetohydroxyacid synthase I.
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大肠杆菌 K-12 的 ilvB 基因座是编码乙酰羟酸合酶 I 两个亚基的操纵子。
DOI：
10.1093/nar/13.11.3979
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发表时间：
1985
影响因子：
14.9
通讯作者：
Silverman,PM
中科院分区：
文献类型：
--
作者：
Friden,P;Donegan,J;Mullen,J;Tsui,P;Freundlich,M;Eoyang,L;Weber,R;Silverman,PM
大肠杆菌K-12的ilvB基因座包含两个开放的阅读框，限定了分子量为60，000和11，200的多肽。整个基因座，约2.3 kb，共转录为一个操纵子。假定的操纵子多肽的分子量和氨基酸组成与乙酰羟酸合酶（AHAS）I的大小亚基多肽的分子量和氨基酸组成一致，其中ilvB是结构位点。我们保留名称ilvB用于启动子近端（较长）顺反子，并将启动子远端顺反子命名为ilvN。ilvB多肽的分子量和氨基酸序列与Ilvl（AHAS III的大亚基）和IlvG（AHAS II的大亚基）多肽的分子量和氨基酸序列惊人地相似。IlvN、IlvH（AHAS III的较小亚基）和IlvM（AHAS II的较小亚基）多肽之间的大小均匀性较小。然而，在三种小亚基多肽之间存在显著的氨基酸序列同源性。因此，E. coli K-12可能具有共同的进化起源
The ilvB locus of Escherichia coli K-12 encloses two open reading frames defining polypeptides of 60,000 and 11,200 molecular weight. The entire locus, about 2.3 kb, is co-transcribed as an operon. The molecular weights and amino acid compositions of the presumptive operon polypeptides agree with those of the large and small subunit polypeptides of acetohydroxyacid synthase (AHAS) I, for which ilvB is the structural locus. We reserve the designation ilvB for the promoter proximal (longer) cistron and designate the promoter distal cistron ilvN. The molecular weight and amino acid sequence of the ilvB polypeptide are strikingly similar to those of the Ilvl (larger subunit of AHAS III) and IlvG (larger subunit of AHAS II) polypep-tides. There is less size uniformity among the IlvN, IlvH (smaller sub-unit of AHAS III), and IlvM (smaller subunit of AHAS II) polypeptides. Nevertheless, there is significant amino acid sequence homology among the three small subunit polypeptides. Thus, all three AHAS isozymes of E. coli K-12 probably have a common evolutionary origin