Reversible thermal transition in GrpE, the nucleotide exchange factor of the DnaK heat-shock system.


Abstract

DnaK, a Hsp70 acting in concert with its co-chaperones DnaJ and GrpE, is essential for Escherichia coli to survive environmental stress, including exposure to elevated temperatures. Here we explored the influence of temperature on the structure of the individual components and the functional properties of the chaperone system. GrpE undergoes extensive but fully reversible conformational changes in the physiologically relevant temperature range (transition midpoint at approximately 48 degrees C), as observed with both circular dichroism measurements and differential scanning calorimetry, whereas no thermal transitions occur in DnaK and DnaJ between 15 degrees C and 48 degrees C. The conformational changes in GrpE appear to be important in controlling the interconversion of T-state DnaK (ATP-liganded, low affinity for polypeptide substrates) and R-state DnaK (ADP-liganded, high affinity for polypeptide substrates). The rate of the T --> R conversion of DnaK due to DnaJ-triggered ATP hydrolysis follows an Arrhenius temperature dependence. In contrast, the rate of the R --> T conversion due to GrpE-catalyzed ADP/ATP exchange increases progressively less with increasing temperature and even decreases at temperatures above approximately 40 degrees C, indicating a temperature-dependent reversible inactivation of GrpE. At heat-shock temperatures, the reversible structural changes of GrpE thus shift DnaK toward its high-affinity R state. Study holds ProTherm entries: 10527, 10528 Extra Details: environmental stress; conformational changes; affinity;,temperature dependence

Submission Details

ID: feXxGnES3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:40 p.m.

Version: 1

Publication Details
Grimshaw JP;Jelesarov I;Schönfeld HJ;Christen P,J. Biol. Chem. (2001) Reversible thermal transition in GrpE, the nucleotide exchange factor of the DnaK heat-shock system. PMID:11084044
Additional Information

Sequence Assay Result Units