site-directed mutations in the c-terminal extension of human αb-crystallin affect chaperone function and block amyloid fibril formation定点突变的c端扩展人类αb-crystallin影响伴侣功能并阻止淀粉样原纤维形成.pdf

Site-Directed Mutations in the C-Terminal Extension of Human aB-Crystallin Affect Chaperone Function and Block Amyloid Fibril Formation 1,2 3 3 4 3 5 Teresa M. Treweek , Heath Ecroyd , Danielle M. Williams , Sarah Meehan , John A. Carver , Mark J. Walker * 1 Department of Chemistry, University of Wollongong, Wollongong, New South Wales, Australia, 2 Graduate School of Medicine, University of Wollongong, Wollongong, New South Wales, Australia, 3 School of Chemistry and Physics, The University of Adelaide, Adelaide, South Australia, Australia, 4 The University Chemical Laboratory, University of Cambridge, Cambridge, United Kingdom, 5 School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia Background. Alzheimer’s, Parkinson’s and Creutzfeldt-Jakob disease are associated with inappropriate protein deposition and ordered amyloid fibril assembly. Molecular chaperones, including aB-crystallin, play a role in the prevention of protein deposition. Methodology/Principal Findings. A series of site-directed mutants of the human molecular chaperone, aB- crystallin, were constructed which focused on the flexible C-terminal extension of the protein. We investigated the structural role of this region as well as its role in the chaperone function of aB-crystallin under different types of protein aggregation, i.e. disordered amorphous aggregation and ordered amyloid fibril assembly. It was found that mutation of lysine and glutamic acid residues in the C-terminal extension of aB-crystallin resulted in proteins that had improved chaperone activity against amyloid fibril forming target proteins compared to the wild-type protein. Conclusions/Significance. Together, our results highlight the important role of the C-termi