title: Transcriptional organization and regulation of the dnaK and groE operons of Chlamydia trachomatis.
abstract: The transcriptional organization and regulation of the dnaK and groE heat shock operons of Chlamydia trachomatis were studied and found to resemble those of the cognate operons of Bacillus subtilis and Clostridium acetobutylicum. The gene order is conserved (hrcA-grpE-dnaK), but no dnaJ homolog could be identified in this region. The dnaK operon was transcribed as a low-abundance polycistronic mRNA whose levels did not increase upon exposure to heat shock. In contrast, a more abundant 2.3-kb mRNA encoding only the dnaK sequence was detectable, and its steady-state level increased upon heat shock. The transcription initiation sites of the dnaK and groE operons were found to be preceded by sequences that resemble an Escherichia coli sigma70 consensus promoter. Upstream of each putative promoter is an inverted repeat sequence which resembles a similar element (CIRCE [controlling inverted repeat of chaperone expression]) found upstream of the dnaK and groE operons in at least 27 eubacterial species. In vitro transcription studies utilizing partially purified C. trachomatis RNA polymerase demonstrated that the regions containing the putative promoter elements of the dnaK and groE operons are functional, although heat shock-regulated expression could not be demonstrated.
authors.affiliation: Department of Medicine, University of California, San Francisco, 94143-0654, USA.
authors.forename: M
authors.initials: M
authors.lastname: Tan
authors.forename: B
authors.initials: B
authors.lastname: Wong
authors.forename: J N
authors.initials: JN
authors.lastname: Engel
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D018833:Chaperonins; D002692:Chlamydia trachomatis / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D006360:Heat-Shock Proteins / Q000235:genetics*; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009876:Operon; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012260:Ribonucleases / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C028715:GroE protein, E coli; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012260:Ribonucleases; D018833:Chaperonins; C063842:dnaK protein, E coli