色氨酸转运RNA在调控大肠杆菌与枯草芽孢杆菌中trp操纵子表达方面的不同作用。

The different roles of tryptophan transfer RNA in regulating trp operon expression in E. coli versus B. subtilis.

作者信息

Yanofsky Charles

机构信息

Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA.

出版信息

Trends Genet. 2004 Aug;20(8):367-74. doi: 10.1016/j.tig.2004.06.007.

DOI:10.1016/j.tig.2004.06.007

PMID:15262409

Abstract

Escherichia coli and Bacillus subtilis use different mechanisms of sensing and responding to tryptophan and uncharged tRNA(Trp) as regulatory signals. In E. coli, tryptophan activates a repressor that binds to the trp promoter- operator, inhibiting transcription initiation. In B. subtilis, tryptophan activates an RNA-binding protein, TRAP, which binds to the trp operon leader RNA, causing transcription termination. In E. coli uncharged tRNA(Trp) accumulation stalls the ribosome attempting translation of tandem Trp codons in the leader-peptide coding region of the operon. This stalling permits the formation of an RNA antiterminator structure, preventing transcription termination. In B. subtilis uncharged tRNA(Trp) accumulation activates transcription and translation of the at operon. AT protein inhibits tryptophan-activated TRAP, thereby preventing TRAP-mediated transcription termination. These differences might reflect the unique organizational features of the respective trp operons and their ancestry.

摘要

大肠杆菌和枯草芽孢杆菌利用不同的机制来感知色氨酸和无电荷的tRNA（Trp），并将其作为调节信号做出反应。在大肠杆菌中，色氨酸激活一种阻遏蛋白，该蛋白与trp启动子 - 操纵基因结合，抑制转录起始。在枯草芽孢杆菌中，色氨酸激活一种RNA结合蛋白TRAP，它与trp操纵子前导RNA结合，导致转录终止。在大肠杆菌中，无电荷的tRNA（Trp）积累会使核糖体在操纵子前导肽编码区中串联的Trp密码子处尝试翻译时停滞。这种停滞允许形成一种RNA抗终止子结构，防止转录终止。在枯草芽孢杆菌中，无电荷的tRNA（Trp）积累激活at操纵子的转录和翻译。AT蛋白抑制色氨酸激活的TRAP，从而防止TRAP介导的转录终止。这些差异可能反映了各自trp操纵子的独特组织特征及其起源。