title: Iron-Sulfur Cluster Biogenesis Chaperones: Evidence for Emergence of Mutational Robustness of a Highly Specific Protein-Protein Interaction.
abstract: Biogenesis of iron-sulfur clusters (FeS) is a highly conserved process involving Hsp70 and J-protein chaperones. However, Hsp70 specialization differs among species. In most eukaryotes, including Schizosaccharomyces pombe, FeS biogenesis involves interaction between the J-protein Jac1 and the multifunctional Hsp70 Ssc1. But, in Saccharomyces cerevisiae and closely related species, Jac1 interacts with the specialized Hsp70 Ssq1, which emerged through duplication of SSC1. As little is known about how gene duplicates affect the robustness of their protein interaction partners, we analyzed the functional and evolutionary consequences of Ssq1 specialization on the ubiquitous J-protein cochaperone Jac1, by comparing S. cerevisiae and S. pombe. Although deletion of JAC1 is lethal in both species, alanine substitutions within the conserved His-Pro-Asp (HPD) motif, which is critical for Jac1:Hsp70 interaction, have species-specific effects. They are lethal in S. pombe, but not in S. cerevisiae. These in vivo differences correlated with in vitro biochemical measurements. Charged residues present in the J-domain of S. cerevisiae Jac1, but absent in S. pombe Jac1, are important for tolerance of S. cerevisiae Jac1 to HPD alterations. Moreover, Jac1 orthologs from species that encode Ssq1 have a higher sequence divergence. The simplest interpretation of our results is that Ssq1's coevolution with Jac1 resulted in expansion of their binding interface, thus increasing the efficiency of their interaction. Such an expansion could in turn compensate for negative effects of HPD substitutions. Thus, our results support the idea that the robustness of Jac1 emerged as consequence of its highly efficient and specific interaction with Ssq1.
authors.affiliation: Laboratory of Evolutionary Biochemistry, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Delewski
authors.affiliation: Laboratory of Evolutionary Biochemistry, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland.
authors.forename: Bogumiła
authors.initials: B
authors.lastname: Paterkiewicz
authors.affiliation: Laboratory of Evolutionary Biochemistry, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland.
authors.forename: Mateusz
authors.initials: M
authors.lastname: Manicki
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison.
authors.forename: Brenda
authors.initials: B
authors.lastname: Schilke
authors.affiliation: Laboratory of Evolutionary Biochemistry, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland.
authors.forename: Bartłomiej
authors.initials: B
authors.lastname: Tomiczek
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison.
authors.forename: Szymon J
authors.initials: SJ
authors.lastname: Ciesielski
authors.affiliation: Department of Physical Chemistry, Gdansk University of Technology, Gdansk, Poland.
authors.forename: Lukasz
authors.initials: L
authors.lastname: Nierzwicki
authors.affiliation: Department of Physical Chemistry, Gdansk University of Technology, Gdansk, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Czub
authors.affiliation: Laboratory of Evolutionary Biochemistry, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland.
authors.forename: Rafal
authors.initials: R
authors.lastname: Dutkiewicz
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison ecraig@wisc.edu jaroslaw.marszalek@biotech.ug.edu.pl.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Craig
authors.affiliation: Laboratory of Evolutionary Biochemistry, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Gdansk, Poland Department of Biochemistry, University of Wisconsin-Madison ecraig@wisc.edu jaroslaw.marszalek@biotech.ug.edu.pl.
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Marszalek
mesh_terms: D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D050296:Microbial Viability / Q000235:genetics; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D060066:Protein Interaction Maps; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D013455:Sulfur
chemical_list: D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D013455:Sulfur; D007501:Iron
keywords: Hsp70 chaperones; J-protein cochaperones; gene duplication; mitochondria; protein coevolution