title: Oligomeric structure and chaperone-like activity of Drosophila melanogaster mitochondrial small heat shock protein Hsp22 and arginine mutants in the alpha-crystallin domain.
abstract: The structure and chaperone function of DmHsp22WT, a small Hsp of Drosophila melanogaster localized within mitochondria were examined. Mutations of conserved arginine mutants within the alpha-crystallin domain (ACD) domain (R105G, R109G, and R110G) were introduced, and their effects on oligomerization and chaperone function were assessed. Arginine to glycine mutations do not induce significant changes in tryptophan fluorescence, and the mutated proteins form oligomers that are of equal or smaller size than the wild-type protein. They all form oligomer with one single peak as determined by size exclusion chromatography. While all mutants demonstrate the same efficiency as the DmHsp22WT in a DTT-induced insulin aggregation assay, all are more efficient chaperones to prevent aggregation of malate dehydrogenase. Arginine mutants of DmHsp22 are efficient chaperones to retard aggregation of CS and Luc. In summary, this study shows that mutations of arginine to glycine in DmHsp22 ACD induce a number of structural changes, some of which differ from those described in mammalian sHsps. Interestingly, only the R110G-DmHsp22 mutant, and not the expected R109G equivalent to human R140-HspB1, R116-HspB4, and R120-HspB5, showed different structural properties compared with the DmHsp22WT.
authors.affiliation: Laboratoire de génétique cellulaire et développementale, Département de biologie moléculaire, de biochimie médicale et de pathologie, Faculté de médecine, Institut de biologie intégrative et des systèmes (IBIS) and PROTEO, Université Laval, Québec, Québec, G1V 0A6, Canada.
authors.forename: Afrooz
authors.initials: A
authors.lastname: Dabbaghizadeh
authors.affiliation: IMPMC UMR7590, CNRS, Sorbonne-Universités, MNHN, IRD, 4 place Jussieu, Paris, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Finet
authors.affiliation: Laboratoire de génétique cellulaire et développementale, Département de biologie moléculaire, de biochimie médicale et de pathologie, Faculté de médecine, Institut de biologie intégrative et des systèmes (IBIS) and PROTEO, Université Laval, Québec, Québec, G1V 0A6, Canada.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Morrow
authors.affiliation: Laboratoire de génétique cellulaire et développementale, Département de biologie moléculaire, de biochimie médicale et de pathologie, Faculté de médecine, Institut de biologie intégrative et des systèmes (IBIS) and PROTEO, Université Laval, Québec, Québec, G1V 0A6, Canada.
authors.forename: Mohamed Taha
authors.initials: MT
authors.lastname: Moutaoufik
authors.affiliation: Laboratoire de génétique cellulaire et développementale, Département de biologie moléculaire, de biochimie médicale et de pathologie, Faculté de médecine, Institut de biologie intégrative et des systèmes (IBIS) and PROTEO, Université Laval, Québec, Québec, G1V 0A6, Canada. robert.tanguay@fmed.ulaval.ca.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Tanguay
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry* / Q000235:genetics; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics; D004331:Drosophila melanogaster / Q000737:chemistry* / Q000235:genetics; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000235:genetics; D017354:Point Mutation; D011487:Protein Conformation; D055503:Protein Multimerization; D016415:Sequence Alignment; D038201:alpha-Crystallins / Q000737:chemistry* / Q000235:genetics
chemical_list: D029721:Drosophila Proteins; D006360:Heat-Shock Proteins; C490752:Hsp22 protein, Drosophila; D024101:Mitochondrial Proteins; D038201:alpha-Crystallins; D001120:Arginine
keywords: Alpha-crystallin domain (ACD); Chaperone assays; DmHsp22; Drosophila melanogaster; Mitochondria; Small heat shock protein (sHsp)