title: Identification and characterization of the cognate anti-sigma factor and specific promoter elements of a T. tengcongensis ECF sigma factor.
abstract: Extracytoplasmic function (ECF) σ factors, the largest group of alternative σ factors, play important roles in response to environmental stresses. Tt-RpoE1 is annotated as an ECF σ 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-σ 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 σ(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 σ factors in adaptive response regulation of the related genes.
authors: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, People's Republic of China.
authors: Jingfang
authors: J
authors: Liu
authors: Jie
authors: J
authors: Li
authors: Zhenfang
authors: Z
authors: Wu
authors: Huadong
authors: H
authors: Pei
authors: Jian
authors: J
authors: Zhou
authors: Hua
authors: H
authors: Xiang
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003593:Cytoplasm / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000235:genetics; D012808:Sigma Factor / Q000737:chemistry / Q000235:genetics*; D046968:Thermoanaerobacter / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012808:Sigma Factor