title: DnaK-Dependent Accelerated Evolutionary Rate in Prokaryotes.
abstract: Many proteins depend on an interaction with molecular chaperones in order to fold into a functional tertiary structure. Previous studies showed that protein interaction with the GroEL/GroES chaperonine and Hsp90 chaperone can buffer the impact of slightly deleterious mutations in the protein sequence. This capacity of GroEL/GroES to prevent protein misfolding has been shown to accelerate the evolution of its client proteins. Whether other bacterial chaperones have a similar effect on their client proteins is currently unknown. Here, we study the impact of DnaK (Hsp70) chaperone on the evolution of its client proteins. Evolutionary parameters were derived from comparison of the Escherichia coli proteome to 1,808,565 orthologous proteins in 1,149 proteobacterial genomes. Our analysis reveals a significant positive correlation between protein binding frequency with DnaK and evolutionary rate. Proteins with high binding affinity to DnaK evolve on average 4.3-fold faster than proteins in the lowest binding affinity class at the genus resolution. Differences in evolutionary rates of DnaK interactor classes are still significant after adjusting for possible effects caused by protein expression level. Furthermore, we observe an additive effect of DnaK and GroEL chaperones on the evolutionary rates of their common interactors. Finally, we found pronounced similarities in the physicochemical profiles that characterize proteins belonging to DnaK and GroEL interactomes. Our results thus implicate DnaK-mediated folding as a major component in shaping protein evolutionary dynamics in bacteria and supply further evidence for the long-term manifestation of chaperone-mediated folding on genome evolution.
authors.affiliation: Institute of General Microbiology, Christian-Albrechts Universtiy of Kiel, Kiel, Germany.
authors.forename: A Samer
authors.initials: AS
authors.lastname: Kadibalban
authors.affiliation: Present address: The Department of Life Sciences & the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Bogumil
authors.affiliation: Institute of General Microbiology, Christian-Albrechts Universtiy of Kiel, Kiel, Germany.
authors.forename: Giddy
authors.initials: G
authors.lastname: Landan
authors.affiliation: Institute of General Microbiology, Christian-Albrechts Universtiy of Kiel, Kiel, Germany tdagan@ifam.uni-kiel.de.
authors.forename: Tal
authors.initials: T
authors.lastname: Dagan
mesh_terms: D018834:Chaperonin 60 / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D016680:Genome, Bacterial; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics; D018832:Molecular Chaperones / Q000235:genetics*; D011485:Protein Binding / Q000235:genetics; D020543:Proteome / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics
chemical_list: D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D020543:Proteome; C063842:dnaK protein, E coli
keywords: GroEL; chaperones; genome evolution; microbial evolution