RseB Binding to the Periplasmic Domain of RseA Modulates the RseA:ςE Interaction in the Cytoplasm and the Availability of ςE·RNA Polymerase

• Published in: The Journal of biological chemistry 2000-10, Vol.275 (43), p.33898-33904
• Main Authors: Collinet, Bruno, Yuzawa, Harumi, Chen, Thomas, Herrera, Christian, Missiakas, Dominique
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M006214200

The Escherichia coli ςEregulon 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 ςE RNA polymerase. The N-terminal domain of RseA sequesters ςE 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 ςE:RseA:RseB is 2:5:1 and this ratio remains unaltered upon heat shock induction of the ςE regulon. Purification from crude cellular extracts yields cytoplasmic, soluble ςE RNA polymerase as well as membrane sequestered ςE·RseA and ςE·RseA·RseB. RseB binding to the C-terminal domain of RseA increases the affinity of RseA for ςE 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-RseA interaction represents a measure for misfolded polypeptides in the bacterial envelope, modulating the assembly of ςE RNA polymerase and the cellular heat shock response.