A summary of our findings regarding the CP376 GroEL mutant.

<p>For simplicity, only one ring of the GroEL 14-mer is shown. In wild type GroEL (<i>upper</i>), the apical domains are arranged about the heptameric ring in an orderly fashion, and through Phase C, act in a coordinated manner to encapsulate and sequester folding intermediates of rhodanese. In CP376 (<i>lower</i>) however, this orderly orientation is disrupted, and both static and dynamic characteristics of encapsulation are affected. The dynamic aspects of apical domain disorder were observed by the disappearance of the Phase C kinetic transition in stopped-flow experiments, and the static consequences were reflected in an incomplete encapsulation of refolding rhodanese molecules that resulted in Proteinase K sensitivity of the football complex, as well as an ability to bind the cochaperonin GroES in the absence of ATP. Electron micrographs, CD spectra, and stopped-flow assays suggested that these results were caused by an increased flexibility of the apical domain as a functional unit, rather than by an unfolding of this domain caused by circular permutation (for example, the tryptophan fluorescence of CP376-RW continued to reflect various conformational changes of the GroEL subunit in a manner analogous to the wild type subunit).