title: RseB binding to the periplasmic domain of RseA modulates the RseA:sigmaE interaction in the cytoplasm and the availability of sigmaE.RNA polymerase.
abstract: The Escherichia coli sigmaE regulon has evolved to sense the presence of misfolded proteins in the bacterial envelope. Expression of periplasmic chaperones and folding catalysts is under the control of sigmaE RNA polymerase. The N-terminal domain of RseA sequesters sigmaE in the cytoplasmic membrane, preventing its association with core RNA polymerase. The C-terminal domain of RseA interacts with RseB, a periplasmic protein. The relative concentration of sigmaE:RseA:RseB is 2:5:1 and this ratio remains unaltered upon heat shock induction of the sigmaE regulon. Purification from crude cellular extracts yields cytoplasmic, soluble sigmaE RNA polymerase as well as membrane sequestered sigmaE.RseA and sigmaE.RseA.RseB. RseB binding to the C-terminal domain of RseA increases the affinity of RseA for sigmaE by 2- to 3-fold (Kd 50-100 nM). RseB binds also to the misfolded aggregates of MalE31, a variant of maltose binding protein that forms inclusion bodies in the periplasm. We discuss a model whereby the RseB-RiseA interaction represents a measure for misfolded polypeptides in the bacterial envelope, modulating the assembly of sigmaE RNA polymerase and the cellular heat shock response.
authors.affiliation: Department of Microbiology, Immunology & Molecular Genetics, University of California at Los Angeles, California 90095, USA
authors.forename: B
authors.initials: B
authors.lastname: Collinet
authors.forename: H
authors.initials: H
authors.lastname: Yuzawa
authors.forename: T
authors.initials: T
authors.lastname: Chen
authors.forename: C
authors.initials: C
authors.lastname: Herrera
authors.forename: D
authors.initials: D
authors.lastname: Missiakas
mesh_terms: D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D018869:Heat-Shock Response; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D009004:Monosaccharide Transport Proteins; D009154:Mutation; D019897:Periplasm / Q000378:metabolism; D033902:Periplasmic Binding Proteins; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D018085:Regulon; D012808:Sigma Factor / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C461619:MalE protein, E coli; D058619:Maltose-Binding Proteins; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; C433802:RseA protein, E coli; D012808:Sigma Factor; D014157:Transcription Factors; C461599:maltose transport system, E coli; C063202:sporulation-specific sigma factors; D012321:DNA-Directed RNA Polymerases