groEL

Each subunit is composed of an apical domain that binds non-folded proteins and GroES, an intermediate domain and an equatorial domain that binds ATP and is involved in inter-ring interactions (PubMed:16288915, PubMed:7935790). Forms a large central channel that appears to traverse the entire length of the cylinder with no obstruction (PubMed:7935790). The central channel of GroEL functions as two cavities, one in each ring, that are separated from each other by the crystallographically disordered 23-amino-acid C-terminal segments of the seven subunits (PubMed:9285585). The entry and exit of polypeptide seem to be restricted to the apical end of each ring (PubMed:9285585).

Modulating the volume of the GroEL central cavity affects folding speed in accordance with confinement theory. Small proteins fold more rapidly as the size of the cage is gradually reduced to a point where restriction in space slows folding dramatically. For larger proteins, either expanding or reducing cage volume decelerate folding (PubMed:16751100). A stepwise reduction in cage size results in a gradual loss of cell viability (PubMed:18418386).

Together with its co-chaperonin GroES, plays an essential role in assisting protein folding (PubMed:10532860, PubMed:16751100, PubMed:1676490, PubMed:18418386, PubMed:18987317, PubMed:20603018, PubMed:24816391, PubMed:2573517, PubMed:2897629, PubMed:8104102, PubMed:9285593). The GroEL-GroES system forms a nano-cage that allows encapsulation of the non-native substrate proteins and provides a physical environment optimized to promote and accelerate protein folding, probably by preventing aggregation and by entropically destabilizing folding intermediates (PubMed:16751100, PubMed:18418386, PubMed:18987317, PubMed:20603018, PubMed:24816391). Rapid binding of ATP, followed by slower binding of the non-native substrate protein and GroES to the cis open ring of GroEL initiates productive folding of the non-native protein inside a highly stable GroEL-ATP-GroES complex (PubMed:19915138, PubMed:22445172, PubMed:9285585, PubMed:9285593). Binding of ATP and GroES induces conformational changes that result in the release of the substrate protein into a nano-cage compartment, within the GroEL central cavity, for folding in isolation (PubMed:16684774, PubMed:22445172, PubMed:8861908, PubMed:9285585). To discharge GroES and substrate protein, ATP hydrolysis in the cis ring is required to form a GroEL-ADP-GroES complex with decreased stability (PubMed:9285593). Finally, binding of ATP to the opposite trans ring of GroEL results in disassembly of the cis-ternary complex, which opens the cage and allows release of the folded protein (PubMed:9285585, PubMed:9285593). Proteins released in non-native form may be rapidly rebound by another GroEL complex until all of the initially bound polypeptide reaches native form (PubMed:7867798, PubMed:7915201). Can rescue kinetically trapped intermediates (PubMed:20603018). GroEL shows ATPase activity (PubMed:1676490, PubMed:379350, PubMed:9285593). ATP hydrolysis moves the reaction cycle forward but is not required for substrate folding (PubMed:9285593).

Also plays a role in coupling between replication of the F plasmid and cell division of the cell.

(Microbial infection) Essential for the assembly of several bacteriophages.

Phosphorylated reversibly during heat shock.

Belongs to the chaperonin (HSP60) family.

• Cytoplasm
• Uniformly located in the cytoplasm (PubMed:20094032). Exclusively localized in foci, usually near 1 cell pole in mid-to-late exponential phase (PubMed:22380631); polar localization depends on the minCDE operon. Foci form near midcell (Probable).

groL, mopA, b4143, JW4103, groEL, Chaperonin GroEL, 60 kDa chaperonin, Chaperonin-60, GroEL protein, Cpn60

• swissprot:P0A6F5

Proteins

Immunology & Infectious Disease

57329Da