Identification and Characterization of the Cognate Anti-Sigma Factor and Specific Promoter Elements of a T. tengcongensis ECF Sigma Factor----中国科学院微生物研究所

科研成果

论文题目:	Identification and Characterization of the Cognate Anti-Sigma Factor and Specific Promoter Elements of a T. tengcongensis ECF Sigma Factor
作者:	Liu, JF; Li, J; Wu, ZF; Pei, HD; Zhou, J; Xiang, H
联系作者:	Liu, JF
刊物名称:	PLOS ONE
期:	7
卷:	7
页:
年份:	2012
影响因子:	4.092
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摘要:	Extracytoplasmic function (ECF) sigma factors, the largest group of alternative s factors, play important roles in response to environmental stresses. Tt-RpoE1 is annotated as an ECF sigma factor in Thermoanaerobacter tengcongensis. In this study, we revealed that the Tt-tolB gene located downstream of the Tt-rpoE1 gene encoded the cognate anti-sigma factor, which could inhibit the transcription activity of Tt-RpoE1 by direct interaction with Tt-RpoE1 via its N-terminal domain. By in vitro transcription assay, the auto-regulation ability of Tt-RpoE1 was determined, and band shift assay showed that Tt-RpoE1 preferred to bind a fork-junction promoter DNA. With truncation or base-specific scanning mutations, the contribution of the nucleotides in -35 and -10 regions to interaction between Tt-RpoE1 and promoter DNA was explored. The promoter recognition pattern of Tt-RpoE1 was determined as 5' tGTTACN(16)CGTC 3', which was further confirmed by in vitro transcription assays. This result showed that the Tt-RpoE1-recognized promoter possessed a distinct -10 motif (-13CGTC-10) as the recognition determinant, which is distinguished from the -10 element recognized by sigma(70). Site-directed mutagenesis in Region 2.4 of Tt-RpoE1 indicated that the "D" residue of DXXR motif was responsible for recognizing the -12G nucleotide. Our results suggested that distinct -10 motif may be an efficient and general strategy used by ECF sigma factors in adaptive response regulation of the related genes.