文章基本信息

标题：FlbD of Caulobacter crescentus is a homologue of the NtrC (NRI) protein and activates sigma 54-dependent flagellar gene promoters
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作者：G Ramakrishnan ; A Newton
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：6
页码：2369-2373
DOI：10.1073/pnas.87.6.2369
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The periodic transcription of flagellar genes in the Caulobacter crescentus cell cycle is controlled, in part, by their organization in a regulatory hierarchy. The flbG (hook operon), flaN, and flagellin gene operons, which are at the lowest levels of the hierarchy and expressed late in the cell cycle, contain Ntr-like promoters. We report that flbD, one of the early genes required in trans for expression of these operons, codes for a 52-kDa protein homologous to the transcriptional activators NtrC (NRI), NifA, DctD, HydG, and XylR. Our results show that in Escherichia coli flbD partially complements glnG (ntrC) mutations and stimulates transcription of the C. crescentus sigma 54 RNA polymerase-dependent flbG gene. Additionally, the sequence predicts that FlbD protein, along with NtrC, DctD, and HydG proteins, is structurally related at the amino-terminal domain to a larger family of response regulators that mediate cellular responses to environmental stimuli. FlbD may be a singular member of this large protein family in that its function is tied to an internal cell-cycle signal. FlbD is also unusual in that its amino-terminal domain contains only one of the three residues conserved in previously described members of this family of response regulators.