title: The DNLZ/HEP zinc-binding subdomain is critical for regulation of the mitochondrial chaperone HSPA9.
abstract: Human mitochondrial DNLZ/HEP regulates the catalytic activity and solubility of the mitochondrial hsp70 chaperone HSPA9. Here, we investigate the role that the DNLZ zinc-binding and C-terminal subdomains play in regulating HSPA9. We show that truncations lacking portions of the zinc-binding subdomain (ZBS) do not affect the solubility of HSPA9 or its ATPase domain, whereas those containing the ZBS and at least 10 residues following this subdomain enhance chaperone solubility. Binding measurements further show that DNLZ requires its ZBS to form a stable complex with the HSPA9 ATPase domain, and ATP hydrolysis measurements reveal that the ZBS is critical for full stimulation of HSPA9 catalytic activity. We also examined if DNLZ is active in vivo. We found that DNLZ partially complements the growth of Δzim17 Saccharomyces cerevisiae, and we discovered that a Zim17 truncation lacking a majority of the C-terminal subdomain strongly complements growth like full-length Zim17. These findings provide direct evidence that human DNLZ is a functional ortholog of Zim17. In addition, they implicate the pair of antiparallel β-strands that coordinate zinc in Zim17/DNLZ-type proteins as critical for binding and regulating hsp70 chaperones.
authors.affiliation: Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77251, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Vu
authors.forename: Peng
authors.initials: P
authors.lastname: Zhai
authors.forename: Juhye
authors.initials: J
authors.lastname: Lee
authors.forename: Cecilia
authors.initials: C
authors.lastname: Guerra
authors.forename: Shirley
authors.initials: S
authors.lastname: Liu
authors.forename: Michael C
authors.initials: MC
authors.lastname: Gustin
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Silberg
mesh_terms: D005816:Genetic Complementation Test; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D030781:Organisms, Genetically Modified; D054730:Protein Interaction Domains and Motifs / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000378:metabolism*; D016335:Zinc Fingers / Q000235:genetics / Q000502:physiology
chemical_list: C559905:DNLZ protein, human; D018840:HSP70 Heat-Shock Proteins; C492001:HSPA9 protein, human; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; C495990:Zim17 protein, S cerevisiae; D015032:Zinc