Three-dimensional structure of Mycobacterium tuberculosis chaperonin-10 reveals a partially stable conformation of its mobile loop

Abstract

The 60 kDa and 10 kDa chaperonins form a unique multimeric complex that mediates several intracellular protein-folding reactions. The 10 kDa chaperonins interact with the 60 kDa chaperonins through a 17-residue long mobile loop which is believed to be highly flexible in the uncomplexed chaperonin-10 but adopts a well ordered conformation upon complex formation with chaperonin-60. We have now solved the three-dimensional structure of Mycobacterium tuberculosis chaperonin-10 and report here a partially stable conformation for its mobile loop. Evolutionary arguments and supporting experimental observations suggest additional conformational rearrangements for chaperonin-10s when associating with chaperonin-60.