title: The transcriptional repressor EUO regulates both subsets of Chlamydia late genes.
abstract: The pathogenic bacterium Chlamydia replicates in a eukaryotic host cell via a developmental cycle marked by temporal waves of gene expression. We have previously shown that late genes transcribed by the major chlamydial RNA polymerase, σ(66) RNA polymerase, are regulated by a transcriptional repressor EUO. We now report that EUO also represses promoters for a second subset of late genes that are transcribed by an alternative polymerase called σ(28) RNA polymerase. EUO bound in the vicinity of six σ(28) -dependent promoters and inhibited transcription of each promoter. We used a mutational analysis to demonstrate that the EUO binding site functions as an operator that is necessary and sufficient for EUO-mediated repression of σ(28) -dependent transcription. We also verified specific binding of EUO to σ(66) -dependent and σ(28) -dependent promoters with a DNA immunoprecipitation assay. These findings support a model in which EUO represses expression of both σ(66) -dependent and σ(28) -dependent late genes. We thus propose that EUO is the master regulator of late gene expression in the chlamydial developmental cycle.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of California, Irvine, CA, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rosario
authors.forename: Brett R
authors.initials: BR
authors.lastname: Hanson
authors.forename: Ming
authors.initials: M
authors.lastname: Tan
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D002692:Chlamydia trachomatis / Q000235:genetics* / Q000378:metabolism; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D047468:Immunoprecipitation; D009875:Operator Regions, Genetic; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D012808:Sigma Factor / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C064971:FliA protein, Bacteria; D012097:Repressor Proteins; D012808:Sigma Factor; C096461:sigma 66 factor, Chlamydia