title: Transcriptional regulation of the S-layer protein type I secretion system in Caulobacter crescentus.
abstract: The Gram-negative Caulobacter crescentus exports RsaA, the crystalline S-layer subunit protein using a dedicated type I secretion system. The protein and two transporter genes (rsaADE) are located together, comparable to the Escherichia coli type I hemolysin hlyCABD operon, where read through of a stem loop following hlyCA results in reduced transcription of the hlyBD. Using two genetic approaches and a direct assessment of transcription from regions 5' to the genes we learned that rsaD and rsaE were transcribed together as a separate transcript from rsaA. These results are contrary to previous assumptions about the rsaADE type I secretion gene control and add another theme to the area of type I secretion transcription regulation. It may be that to accommodate the high levels of RsaA secretion, the type I transporters must be transcribed independently from rsaA.
authors.affiliation: University of British Columbia, Department of Microbiology and Immunology, Vancouver, B.C. Canada V6T 1Z3.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Toporowski
authors.forename: John F
authors.initials: JF
authors.lastname: Nomellini
authors.forename: Peter
authors.initials: P
authors.lastname: Awram
authors.forename: Assaf
authors.initials: A
authors.lastname: Levi
authors.forename: John
authors.initials: J
authors.lastname: Smit
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D016935:Caulobacter crescentus / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D021381:Protein Transport / Q000235:genetics*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000032:analysis
chemical_list: D001426:Bacterial Proteins; D008562:Membrane Glycoproteins; C055764:S-layer proteins; D001616:beta-Galactosidase