GroEL to DnaK chaperone network behind the stability modulation of σ³² at physiological temperature in <i>Escherichia coli</i>

Abstract

The stability of heat-shock transcription factor σ(32) in Escherichia coli has long been known to be modulated only by its own transcribed chaperone DnaK. Very few reports suggest a role for another heat-shock chaperone, GroEL, for maintenance of cellular σ(32) level. The present study demonstrates in vivo physical association between GroEL and σ(32) in E. coli at physiological temperature. This study further reveals that neither DnaK nor GroEL singly can modulate σ(32) stability in vivo; there is an ordered network between them, where GroEL acts upstream of DnaK.