title: The complex evolutionary dynamics of Hsp70s: a genomic and functional perspective.
abstract: Hsp70 molecular chaperones are ubiquitous. By preventing aggregation, promoting folding, and regulating degradation, Hsp70s are major factors in the ability of cells to maintain proteostasis. Despite a wealth of functional information, little is understood about the evolutionary dynamics of Hsp70s. We undertook an analysis of Hsp70s in the fungal clade Ascomycota. Using the well-characterized 14 Hsp70s of Saccharomyces cerevisiae, we identified 491 orthologs from 53 genomes. Saccharomyces cerevisiae Hsp70s fall into seven subfamilies: four canonical-type Hsp70 chaperones (SSA, SSB, KAR, and SSC) and three atypical Hsp70s (SSE, SSZ, and LHS) that play regulatory roles, modulating the activity of canonical Hsp70 partners. Each of the 53 surveyed genomes harbored at least one member of each subfamily, and thus establishing these seven Hsp70s as units of function and evolution. Genomes of some species contained only one member of each subfamily that is only seven Hsp70s. Overall, members of each subfamily formed a monophyletic group, suggesting that each diversified from their corresponding ancestral gene present in the common ancestor of all surveyed species. However, the pattern of evolution varied across subfamilies. At one extreme, members of the SSB subfamily evolved under concerted evolution. At the other extreme, SSA and SSC subfamilies exhibited a high degree of copy number dynamics, consistent with a birth-death mode of evolution. KAR, SSE, SSZ, and LHS subfamilies evolved in a simple divergent mode with little copy number dynamics. Together, our data revealed that the evolutionary history of this highly conserved and ubiquitous protein family was surprising complex and dynamic.
authors.affiliation: Laboratory of Evolutionary Biochemistry, Intercollegiate Faculty of Biotechnology, University of Gdansk, Kladki, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Kominek
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Marszalek
authors.forename: Cécile
authors.initials: C
authors.lastname: Neuvéglise
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Craig
authors.forename: Barry L
authors.initials: BL
authors.lastname: Williams
mesh_terms: D000251:Adenosine Triphosphatases / Q000145:classification / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000145:classification / Q000235:genetics*; D005800:Genes, Fungal; D014644:Genetic Variation; D018840:HSP70 Heat-Shock Proteins / Q000145:classification / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000145:classification / Q000235:genetics*; D005810:Multigene Family; D010802:Phylogeny; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000145:classification / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; C060153:KAR2 protein, yeast; D024101:Mitochondrial Proteins; C090869:SSA3 protein, S cerevisiae; C115913:SSQ1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; C494470:SSB2 protein, S cerevisiae
keywords: Ascomycota genomes; birth-and-death; concerted evolution; gene duplication; molecular chaperones; multi gene family