The crystal structure of the GroES co-chaperonin at 2.8 Å resolution

Abstract

The GroES heptamer forms a dome, approximately 75 A in diameter and 30 A high, with an 8 A orifice in the centre of its roof. The 'mobile loop' segment, previously identified as a GroEL binding determinant, is disordered in the crystal structure in six subunits; the single well-ordered copy extends from the bottom outer rim of the GroES dome, suggesting that the cavity within the dome is continuous with the polypeptide binding chamber of GroEL in the chaperonin complex.

GroEL‐Mediated protein folding

“…The contacting loops of GroES are nonordered and flexible in unbound GroES, as indicated by elegant studies mapping a sharp NMR signal to this region of free GroES in solution (Landry et al, 1993); the same loop region becomes ordered upon binding to GroEL, as revealed by broadening of the NMR signal. Correspondingly, this mobile loop region fails to resolve in the crystal structures of unbound GroES, with the exception of one loop of the seven held in a rigid position by a crystal packing contact (Hunt et al, 1996).…”

“…GroEL's cochaperonin partner, GroES, is a smaller structure, a single seven-membered ring of 10-kDa subunits (Hunt et al, 1996;Mande et al, 1996) (Fig. 2) that binds at one or both ends of the GroEL cylinder in the presence of nucleotide (Chandrasekhar et al, 1986;Saibil et al, 1991;Langer et al, 1992;Schmidt et al, 1994b), producing an upward and outward opening of the GroEL apical domains, which nearly doubles the volume of the central channel ( Fig.…”

Firefly luciferase mutants as sensors of proteome stress

“…GroES, on the other hand, is a dome-shaped homoheptameric ring of 10 kDa subunits each that binds to the ends of the GroEL cylinder in the presence of ATP (Hunt et al, 1996) (Figure 6a). The GroEL-GroES machine is a wellorchestrated system where binding of GroES to GroEL leads to allosteric modulation in the GroEL subunits (Xu et al, 1997).…”

Conformational changes in the chaperonin GroEL: new insights into the allosteric mechanism 1 1Edited by A. R. Fersht

“…GroEL is active as a double heptameric ring (Hendrix, 1979;Hemmingsen et al, 1988), with each ring containing a large central cavity in which substrate protein can be bound (Langer et al, 1992;Braig et al, 1993). The cochaperonin GroES also exists as a heptamer and adopts a dome-like structure (Hunt et al, 1996) that can bind to either GroEL ring to form a cap on the central cavity (Chandrasekhar et al, 1986;Saibil et al, 1991;Langer et al, 1992). Figure 1 shows the asymmetric crystal structure of GroEL with GroES bound to one GroEL ring (Xu et al, 1997), showing the packing of the subunits in the assembly and the topology of each subunit.…”