title: Modification in hydrophobic packing of HAMP domain induces a destabilization of the auto-phosphorylation site in the histidine kinase CpxA.
abstract: The histidine kinases belong to the family of two-component systems, which serves in bacteria to couple environmental stimuli to adaptive responses. Most of the histidine kinases are homodimers, in which the HAMP and DHp domains assemble into an elongated helical region flanked by two CA domains. Recently, X-ray crystallographic structures of the cytoplasmic region of the Escherichia coli histidine kinase CpxA were determined and a phosphotransferase-defective mutant, M228V, located in HAMP, was identified. In the present study, we recorded 1 μs molecular dynamics trajectories to compare the behavior of the WT and M228V protein dimers. The M228V modification locally induces the appearance of larger voids within HAMP as well as a perturbation of the number of voids within DHp, thus destabilizing the HAMP and DHp hydrophobic packing. In addition, a disruption of the stacking interaction between F403 located in the lid of the CA domain involved in the auto-phosphorylation and R296 located in the interacting DHp region, is more often observed in the presence of the M228V modification. Experimental modifications R296A and R296D of CpxA have been observed to reduce also the CpxA activity. These observations agree with the destabilization of the R296/F403 stacking, and could be the sign of the transmission of a conformational event taking place in HAMP to the auto-phosphorylation site of histidine kinase. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 670-682, 2016.
authors.affiliation: Institut Pasteur and CNRS UMR 3528, Rue Du Dr Roux, Unité De Bioinformatique Structurale, Paris, 75015, France.
authors.forename: Marlet
authors.initials: M
authors.lastname: Martinez
authors.affiliation: Institut Pasteur and CNRS UMR 3528, Rue Du Dr Roux, Unité De Bioinformatique Structurale, Paris, 75015, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Duclert-Savatier
authors.affiliation: Institut Pasteur and CNRS UMR 3528, Rue Du Dr Roux, Unité De Microbiologie Structurale, Paris, 75015, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Betton
authors.affiliation: Institut Pasteur and CNRS UMR 3528, Rue Du Dr Roux, Unité De Microbiologie Structurale, Paris, 75015, France.
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Alzari
authors.affiliation: Institut Pasteur and CNRS UMR 3528, Rue Du Dr Roux, Unité De Bioinformatique Structurale, Paris, 75015, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Nilges
authors.affiliation: Institut Pasteur and CNRS UMR 3528, Rue Du Dr Roux, Unité De Bioinformatique Structurale, Paris, 75015, France.
authors.forename: Thérèse E
authors.initials: TE
authors.lastname: Malliavin
mesh_terms: D019943:Amino Acid Substitution; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D004926:Escherichia coli / Q000737:chemistry / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics; D020125:Mutation, Missense; D000072417:Protein Domains; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics
chemical_list: D029968:Escherichia coli Proteins; D011494:Protein Kinases; C490475:CpxA protein, E coli
keywords: CpxA; Escherichia coli; HAMP domain; directed mutagenesis; histidine kinase; two-component system