BACTERIAL CHAPERONIN MACHINES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Chaperonins function by interacting with nascent or unfolded polypeptides to prevent misfolding, which otherwise leads to aggregation. Bacterial chaperonins GroEL/GroES are homologues of mitochondrial Hsp60/Hsp10, respectively. GroEL is a 14-meric double-ring complex of 800 kDa in size, whereas its co-chaperonin GroES is a 70-kDa 7-meric single-ring complex. The mechanism by which molecular chaperones promote proper folding is of intense interest. However, most studies have used small proteins or synthetic peptides as model substrates. Limited information is available as to how these chaperones mediate folding and/or assembly of hetero-oligomeric proteins or macromolecular structures. To understand the mechanism underlying chaperonin-assisted protein folding and assembly, we plan to dp the following cryo-EM studies. Specific Aims: 1. To continue using the GroEL double-ring complex as a model for cryo-EM reconstruction with the goal of attaining 4-¿ resolution. 2. To determine three-dimensional structures of single ring mutant of GroEL bound with substrate.