title: Fibril formation of hsp10 homologue proteins and determination of fibril core regions: differences in fibril core regions dependent on subtle differences in amino acid sequence.
abstract: Heat shock protein 10 (hsp10) is a member of the molecular chaperones and works with hsp60 in mediating various protein folding reactions. GroES is a representative protein of hsp10 from Escherichia coli. Recently, we found that GroES formed a typical amyloid fibril from a guanidine hydrochloride (Gdn-HCl) unfolded state at neutral pH. Here, we report that other hsp10 homologues, such as human hsp10 (Hhsp10), rat mitochondrial hsp10 (Rhsp10), Gp31 from T4 phage, and hsp10 from the hyperthermophilic bacteria Thermotoga maritima, also form amyloid fibrils from an unfolded state. Interestingly, whereas GroES formed fibrils from either the Gdn-HCl unfolded state (at neutral pH) or the acidic unfolded state (at pH 2.0-3.0), Hhsp10, Rhsp10, and Gp31 formed fibrils from only the acidic unfolded state. Core peptide regions of these protein fibrils were determined by proteolysis treatment followed by a combination of Edman degradation and mass spectroscopy analyses of the protease-resistant peptides. The core peptides of GroES fibrils were identical for fibrils formed from the Gdn-HCl unfolded state and those formed from the acidic unfolded state. However, a peptide with a different sequence was isolated from fibrils of Hhsp10 and Rhsp10. With the use of synthesized peptides of the determined core regions, it was also confirmed that the identified regions were capable of fibril formation. These findings suggested that GroES homologues formed typical amyloid fibrils under acidic unfolding conditions but that the fibril core structures were different, perhaps owing to differences in local amino acid sequences.
authors.affiliation: Department of Biotechnology, Faculty of Engineering, Tottori University, Koyama-Minami, Tottori 680-8552, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Yagi
authors.forename: Ai
authors.initials: A
authors.lastname: Sato
authors.forename: Akihiro
authors.initials: A
authors.lastname: Yoshida
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Hattori
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hara
authors.forename: Jun
authors.initials: J
authors.lastname: Shimamura
authors.forename: Isao
authors.initials: I
authors.lastname: Sakane
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Hongo
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Mizobata
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kawata
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D018835:Chaperonin 10 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D017510:Protein Folding; D051381:Rats; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D000682:Amyloid; D018835:Chaperonin 10; D014764:Viral Proteins; C063473:gene 31 protein, Enterobacteria phage T4