Molecular determinants of the ATP hydrolysis asymmetry of the CCT chaperonin complex

• Published in: Proteins, structure, function, and bioinformatics Vol. 82; no. 5; pp. 703 - 707
• Main Authors: Chagoyen, Mónica, Carrascosa, José L., Pazos, Florencio, Valpuesta, José M.
• Format: Journal Article
• Language: English
• Published: United States Blackwell Publishing Ltd 01.05.2014; Wiley Subscription Services, Inc
• Subjects: Adenosine Triphosphate - metabolism; assisted protein folding; Chaperonin Containing TCP-1 - chemistry; Chaperonin Containing TCP-1 - metabolism; Conserved Sequence; Databases, Protein; hetero-oligomer; Hydrolysis; Models, Molecular; Protein Subunits - chemistry; Protein Subunits - metabolism; SDP analysis; sequence analysis; specificity-determining positions; sequence analysis; SDP analysis; assisted protein folding; specificity-determining positions; hetero-oligomer
• ISSN: 0887-3585; 1097-0134
• DOI: 10.1002/prot.24510

ABSTRACT The eukaryotic cytosolic chaperonin CCT is a molecular machine involved in assisting the folding of proteins involved in important cellular processes. Like other chaperonins, CCT is formed by a double‐ring structure but, unlike all of them, each ring is composed of eight different, albeit homologous subunits. This complexity has probably to do with the specificity in substrate interaction and with the mechanism of protein folding that takes place during the chaperonin functional cycle, but its detailed molecular basis remains unknown. We have analyzed the known proteomes in search of residues that are differentially conserved in the eight subunits, as predictors of functional specificity (specificity‐determining positions; SDPs). We have found that most of these SDPs are located near the ATP binding site, and that they define four CCT clusters, corresponding to subunits CCT3, CCT6, CCT8 and CCT1/2/4/5/7. Our results point to a spatial organisation of the CCT subunits in two opposite areas of the ring and provide a molecular explanation for the previously described asymmetry in the hydrolysis of ATP. Proteins 2014; 82:703–707. © 2014 Wiley Periodicals, Inc.