Abstract
The folding of many proteins depends on the assistance of chaperonins like GroEL and GroES and involves the enclosure of substrate proteins inside an internal cavity that is formed when GroES binds to GroEL in the presence of ATP. Precisely how assembly of the GroEL-GroES complex leads to substrate protein encapsulation and folding remains poorly understood. Here we use a chemically modified mutant of GroEL (EL43Py) to uncouple substrate protein encapsulation from release and folding. Although EL43Py correctly initiates a substrate protein encapsulation reaction, this mutant stalls in an intermediate allosteric state of the GroEL ring, which is essential for both GroES binding and the forced unfolding of the substrate protein. This intermediate conformation of the GroEL ring possesses simultaneously high affinity for both GroES and non-native substrate protein, thus preventing escape of the substrate protein while GroES binding and substrate protein compaction takes place. Strikingly, assembly of the folding-active GroEL-GroES complex appears to involve a strategic delay in ATP hydrolysis that is coupled to disassembly of the old, ADP-bound GroEL-GroES complex on the opposite ring.
Highlights
For stringent substrate proteins, ATP is required for the assembly of the GroEL-GroES cis complex and the associated steps of substrate protein encapsulation, release and folding [5, 11,12,13]
Because they bind to the same part of a GroEL ring, how does GroES binding lead to substrate protein encapsulation before the non-native protein escapes into solution? In addition, how is substrate protein release and folding coordinated with ATP hydrolysis?
Because we previously demonstrated that the conformation of a bound Rubisco monomer is linked to the conformational state of the GroEL ring [29, 31], we employed labeled Rubisco in a FRET-based assay to examine the conformational shift of the wild-type GroEL (wtGroEL) and EL43Py rings (Fig. 6A)
Summary
ATP is required for the assembly of the GroEL-GroES cis complex and the associated steps of substrate protein encapsulation, release and folding [5, 11,12,13]. EL43Py productively folds substrate proteins like Rubisco
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
