Mishra S, Chandler SA, Williams D, Claxton DP, Koteiche HA, Stewart PL, Benesch JLP, Mchaourab HS. Engineering of a Polydisperse Small Heat-Shock Protein Reveals Conserved Motifs of Oligomer Plasticity.
Structure 2018;
26:1116-1126.e4. [PMID:
29983375 DOI:
10.1016/j.str.2018.05.015]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 04/10/2018] [Accepted: 05/18/2018] [Indexed: 01/21/2023]
Abstract
Small heat-shock proteins (sHSPs) are molecular chaperones that bind partially and globally unfolded states of their client proteins. Previously, we discovered that the archaeal Hsp16.5, which forms ordered and symmetric 24-subunit oligomers, can be engineered to transition to an ordered and symmetric 48-subunit oligomer by insertion of a peptide from human HspB1 (Hsp27). Here, we uncovered the existence of an array of oligomeric states (30-38 subunits) that can be populated as a consequence of altering the sequence and length of the inserted peptide. Polydisperse Hsp16.5 oligomers displayed higher affinity to a model client protein consistent with a general mechanism for recognition and binding that involves increased access of the hydrophobic N-terminal region. Our findings, which integrate structural and functional analyses from evolutionarily distant sHSPs, support a model wherein the modular architecture of these proteins encodes motifs of oligomer polydispersity, dissociation, and expansion to achieve functional diversity and regulation.
Collapse