ABSTRACTIntracellular protein folding is mediated by molecular chaperones, the best studied among which are the chaperonins GroEL and GroES. Conformational changes and allosteric transitions between different metastable states are hallmarks of the chaperonin mechanism. These conformational transitions between three structural domains of GroEL are anchored at two hinges. Although hinges are known to be critical for mediating the communication between different domains of GroEL, the relative importance of hinges on GroEL oligomeric assembly, ATPase activity, conformational changes, and functional activity is not fully characterized. We have exploited the inability ofMycobacterium tuberculosisGroEL2 to functionally complement anEscherichia coligroELmutant to address the importance of hinge residues in the GroEL mechanism. Various chimeras ofM. tuberculosisGroEL2 andE. coliGroEL allowed us to understand the role of hinges and dissect the consequences of oligomerization and substrate binding capability on conformational transitions. The present study explains the concomitant conformational changes observed with GroEL hinge variants and is best supported by the normal mode analysis.IMPORTANCEConformational changes and allosteric transitions are hallmarks of the chaperonin mechanism. We have exploited the inability ofM. tuberculosisGroEL2 to functionally complement a strain ofE. coliin whichgroELexpression is repressed to address the importance of hinges. The significance of conservation at the hinge regions stands out as a prominent feature of the GroEL mechanism in binding to GroES and substrate polypeptides. The hinge residues play a significant role in the chaperonin activityin vivoandin vitro.
Mapping Conformational Transitions in Cyclic AMP Receptor Protein: Crystal Structure and Normal-Mode Analysis of Mycobacterium tuberculosis apo-cAMP Receptor Protein
