Family

GrpE nucleotide exchange factor (IPR000740)

Short name: GrpE

Family relationships

None.

Description

Molecular chaperones are a diverse family of proteins that function to protect proteins in the intracellular milieu from irreversible aggregation during synthesis and in times of cellular stress. The bacterial molecular chaperone DnaK is an enzyme that couples cycles of ATP binding, hydrolysis, and ADP release by an N-terminal ATP-hydrolysing domain to cycles of sequestration and release of unfolded proteins by a C-terminal substrate binding domain. In prokaryotes the grpE protein. Dimeric GrpE is the co-chaperone for DnaK, and acts as a nucleotide exchange factor, stimulating the rate of ADP release 5000-fold [PMID: 8280473]. DnaK is itself a weak ATPase; ATP hydrolysis by DnaK is stimulated by its interaction with another co-chaperone, DnaJ. Thus the co-chaperones DnaJ and GrpE are capable of tightly regulating the nucleotide-bound and substrate-bound state of DnaK in ways that are necessary for the normal housekeeping functions and stress-related functions of the DnaK molecular chaperone cycle.

The X-ray crystal structure of GrpE in complex with the ATPase domain of DnaK revealed that GrpE is an asymmetric homodimer, bent in a manner that favours extensive contacts with only one DnaKATPase monomer [PMID: 15136046]. GrpE does not actively compete for the atomic positions occupied by the nucleotide. GrpE and ADP mutually reduce one another's affinity for DnaK 200-fold, and ATP instantly dissociates GrpE from DnaK.

GO terms

Biological Process

GO:0006457 protein folding

Molecular Function

GO:0000774 adenyl-nucleotide exchange factor activity
GO:0051087 chaperone binding
GO:0042803 protein homodimerization activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
Pfam
PANTHER
PROSITE patterns
PRINTS
HAMAP