title: Dimerization and DNA-dependent aggregation of the Escherichia coli nucleoid protein and chaperone CbpA.
abstract: The Escherichia coli curved DNA-binding protein A (CbpA) is a nucleoid-associated DNA-binding factor and chaperone that is expressed at high levels as cells enter stationary phase. Using a combination of genetics, biochemistry, structural modelling and single-molecule atomic force microscopy we have examined dimerization of, and DNA binding by, CbpA. Our data show that CbpA dimerization is driven by a hydrophobic surface comprising amino acid side chains W287 and L290 located on the same side of an α helix close to the C-terminus of CbpA. Derivatives of CbpA that are unable to dimerize are also unable to bind DNA. Free in solution, CbpA can exist as either a monomer or dimer. However, when bound to DNA, CbpA forms large aggregates that can protect DNA from degradation by nucleases. These CbpA-DNA aggregates are similar in morphology to protein-DNA complexes formed by the DNA-binding protein from starved cells (Dps), the only other stationary phase-specific nucleoid protein. Conversely, protein-DNA complexes formed by Fis, the major growth phase nucleoid protein, have a markedly different appearance.
authors.affiliation: Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Cosgriff
authors.forename: Kiran
authors.initials: K
authors.lastname: Chintakayala
authors.forename: Ya Tsz A
authors.initials: YT
authors.lastname: Chim
authors.forename: Xinyong
authors.initials: X
authors.lastname: Chen
authors.forename: Stephanie
authors.initials: S
authors.lastname: Allen
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Lovering
authors.forename: David C
authors.initials: DC
authors.lastname: Grainger
mesh_terms: D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: C085674:CbpA protein, E coli; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins