Some novel transcription attenuation mechanisms used by bacteria

作者：Charles Yanofsky, Kouacou V. Konan, Joseph P. Sarsero · 发表于：Biochimie · 年份：1996 · DOI：10.1016/s0300-9084(97)86725-9 · 被引用次数：40 · 研究领域：Bacterial Genetics and Biotechnology、RNA and protein synthesis mechanisms、Bacteriophages and microbial interactions

A variety of transcription attenuation mechanisms are used by bacteria to regulate gene and operon expression. This review summarizes previous and current studies designed to elucidate the features of the specific attenuation mechanisms that regulate expression of the tryptophanase (tna) operon of Escherichia coli and the tryptophan (trp) operon of Bacillus subtilis. Initiation of transcription in the tna operon is regulated by catabolite repression. Once initiated, transcription is regulated by tryptophan-induced inhibition of Rho-mediated transcription termination in the leader region of the operon. An operon-encoded leader peptide, TnaC, containing a crucial tryptophan residue, plays an essential role in induction. This peptide appears to act in cis on the ribosome translating tnaC to inhibit its release at the tnaC stop codon. The stalled ribosome would block Rho's access to the tna transcript, thereby preventing termination. Transcription of the trp operon of B subtilis is regulated by an attenuation mechanism that responds to a tryptophan-activated eleven subunit RNA-binding regulatory protein, called TRAP. Activated TRAP binds to repeated GAG sequences in the leader segment of the trp operon transcript, disrupting an RNA antiterminator and promoting formation of a terminator. Activated TRAP also regulates translation of trpG in the folate operon by binding to repeat GAG sequences surrounding the trpG ribosome binding site. A temperature sensitive tryptophanyl-tRNA synt...