The molecular interactions of heat shock protein 47 (Hsp47) and their implications for collagen biosynthesis.
Heat shock protein 47 (Hsp47) is a procollagen/collagen-specific molecular chaperone protein derived from the serpin family of proteins and essential for the early stages of collagen biosynthesis. In this paper, the results of an extensive biophysical analysis of mature recombinant mouse Hsp47 show the existence of both a structurally mesostable monomer with a 5-strand A-sheet and/or a hyperstable trimer; both states have biological activity. It is also demonstrated that Hsp47 is able to bind to a monomeric and partially folded conformation collagen mimic peptide (PPG)(10). Upon peptide binding Hsp47 has the capacity to induce the peptide backbone to fold into a polyproline type II conformation. Induction of this conformation results in (PPG)(10) peptides associating into higher order assemblies with increased stability compared with the monomeric peptide alone. These assemblies are similar to those observed by others (Go, N., and Suezaki, Y. (1973) Biopolymers 12, 1927-1930; Engel, J., Chen, H. T., Prockop, D. J., and Klump, H. (1977) Biopolymers 16, 601-622) when the peptide is dissolved at high concentration and are proposed to be long chains of peptides in a collagen-like configuration. Examination of the biophysical characteristics of both monomeric and trimeric Hsp47-(PPG)(10) complexes is also used to determine that the peptide-binding site does not reside in strand 4 position of sheet A, as observed for other serpins (Skinner, R., Chang, W. S. W., Jin, L., Pei, X., Huntington, J. A., Abrahams, J. P., Carrell, R. W., and Lomas, D. A. (1998) J. Mol. Biol. 283, 9-14), leaving earlier proposals of a binding site near helix A viable.
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Department of Haematology, University of Cambridge, the Wellcome Trust Centre for Molecular Mechanisms in Disease, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, United Kingdom.
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D000818:Animals; D002942:Circular Dichroism; D003094:Collagen / Q000096:biosynthesis*; D004586:Electrophoresis; D050958:HSP47 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008954:Models, Biological; D008958:Models, Molecular; D011485:Protein Binding; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000378:metabolism; D015843:Serpins / Q000737:chemistry / Q000378:metabolism
D050958:HSP47 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D011994:Recombinant Proteins; C494660:SERPINH1 protein, human; D015842:Serine Proteinase Inhibitors; C494661:Serpinh1 protein, mouse; D015843:Serpins; D003094:Collagen