title: Coexpression patterns of sigma(B) regulators in Bacillus subtilis affect sigma(B) inducibility.
abstract: RsbT is an essential component of the pathway that activates the Bacillus subtilis sigma(B) transcription factor in response to physical stress. rsbT is located within an operon that includes the genes for its principal negative regulator (RsbS) and the stress pathway component that it activates (RsbU), as immediate upstream and downstream neighbors. In the current work we demonstrate that RsbT's ability to function is strongly influenced by coexpression with these adjoining genes. When rsbT is expressed at a site displaced from rsbS and rsbU, RsbT accumulates but it is unable to activate sigma(B) following stress. RsbT activity is restored if rsbT is cotranscribed at the alternative site with the genes that normally abut it. Additionally, an rsbS allele whose product allows constitutively high RsbT-dependent sigma(B) activity displays this activity in rsbS merodiploid strains only when cotranscribed with rsbT and is recessive to a wild-type rsbS allele only if the wild-type rsbS gene is not cotranscribed with an rsbT gene of its own. The data suggest that RsbS and RsbT are synthesized in equivalent amounts and interact coincidently with their synthesis to form stable regulatory complexes that maintain RsbT in a state from which it can be stress activated.
authors.affiliation: Department of Microbiology and Immunology, MC7758, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA. zhangs@UTHSCSA.EDU
authors.forename: Shuyu
authors.initials: S
authors.lastname: Zhang
authors.forename: Adam
authors.initials: A
authors.lastname: Reeves
authors.forename: Robyn L
authors.initials: RL
authors.lastname: Woodbury
authors.forename: W G
authors.initials: WG
authors.lastname: Haldenwang
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology*; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000502:physiology; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D012808:Sigma Factor / Q000235:genetics*; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C079011:SigB protein, Bacteria; D012808:Sigma Factor; C119219:RsbT protein, Bacillus subtilis; D017346:Protein Serine-Threonine Kinases; D010744:Phosphoric Monoester Hydrolases; C091162:RsbU protein, Bacillus subtilis; D001616:beta-Galactosidase