title: Oligomerization and chaperone-like activity of Drosophila melanogaster small heat shock protein DmHsp27 and three arginine mutants in the alpha-crystallin domain.
abstract: The small Hsp DmHsp27 from Drosophila melanogaster is one of the few small heat shock proteins (sHsps) found within the nucleus. We report that its dimerization is independent of disulfide bond formation and seems to rely on salt bridges. Unlike metazoan sHsps, DmHsp27 forms two populations of oligomers not in equilibrium. Mutations at highly conserved arginine residues in mammalian sHsps have been reported to be associated with protein conformational defects and intracellular aggregation. Independent mutation of three highly conserved arginines (R122, R131, and R135) to glycine in DmHsp27 results in only one population of higher molecular weight form. In vitro, the chaperone-like activity of wild-type DmHsp27 was comparable with that of its two isolated populations and to the single population of the R122G, R131G, and R135G using luciferase as substrate. However, using insulin, the chaperone-like activity of wild-type DmHsp27 was lower than that of R122G and R131G mutants. Altogether, the results characterize wild-type DmHsp27 and its alpha-crystallin domain (ACD) arginine mutants and may give insight into protection mechanism of sHsps.
authors.affiliation: Laboratoire de génétique cellulaire et développementale, Département de biologie moléculaire, de biochimie médicale et de pathologie, Institut de biologie intégrative et des systèmes (IBIS) and PROTEO, Université Laval, 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, Institut de biologie intégrative et des systèmes (IBIS) and PROTEO, Université Laval, Québec, G1V 0A6, Canada.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Morrow
authors.affiliation: Plate-forme de bio-informatique, Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, G1V 0A6, Canada.
authors.forename: Halim
authors.initials: H
authors.lastname: Maaroufi
authors.affiliation: IMPMC UMR7590, CNRS, UPMC Paris 6, 4 place Jussieu, Paris, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Férard
authors.affiliation: IMPMC UMR7590, CNRS, UPMC Paris 6, 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, Institut de biologie intégrative et des systèmes (IBIS) and PROTEO, Université Laval, 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; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D017354:Point Mutation; D011487:Protein Conformation; D000072417:Protein Domains; D055503:Protein Multimerization; D038201:alpha-Crystallins / Q000737:chemistry*
chemical_list: D029721:Drosophila Proteins; D006360:Heat-Shock Proteins; C087442:Hsp26 protein, Drosophila; D038201:alpha-Crystallins
keywords: Alpha-crystallin domain (ACD); Chaperone; DmHsp27; Drosophila melanogaster; Small heat shock protein (sHsp)