Cpn60 chaperonin GroEL, large subunit of GroESL; Prevents misfolding and promotes the refolding and proper assembly of unfolded polypeptides generated under stress conditions.

Heat shock protein; Participates actively in the response to hyperosmotic and heat shock by preventing the aggregation of stress-denatured proteins, in association with DnaK and GrpE. It is the nucleotide exchange factor for DnaK and may function as a thermosensor. Unfolded proteins bind initially to DnaJ; upon interaction with the DnaJ-bound protein, DnaK hydrolyzes its bound ATP, resulting in the formation of a stable complex. GrpE releases ADP from DnaK; ATP binding to DnaK triggers the release of the substrate protein, thus completing the reaction cycle. Several rounds of ATP-depen [...]

Protein refolding molecular co-chaperone Hsp90, Hsp70-dependent; Molecular chaperone. Has ATPase activity.

Chaperone Hsp40, DnaK co-chaperone; Interacts with DnaK and GrpE to disassemble a protein complex at the origins of replication of phage lambda and several plasmids. Participates actively in the response to hyperosmotic and heat shock by preventing the aggregation of stress-denatured proteins and by disaggregating proteins, also in an autonomous, DnaK-independent fashion. Unfolded proteins bind initially to DnaJ; upon interaction with the DnaJ-bound protein, DnaK hydrolyzes its bound ATP, resulting in the formation of a stable complex. GrpE releases ADP from DnaK; ATP binding to DnaK t [...]

Protein disaggregation chaperone; Part of a stress-induced multi-chaperone system, it is involved in the recovery of the cell from heat-induced damage, in cooperation with DnaK, DnaJ and GrpE. Acts before DnaK, in the processing of protein aggregates. Protein binding stimulates the ATPase activity; ATP hydrolysis unfolds the denatured protein aggregates, which probably helps expose new hydrophobic binding sites on the surface of ClpB-bound aggregates, contributing to the solubilization and refolding of denatured protein aggregates by DnaK.

Molecular chaperone and ATPase component of HslUV protease; ATPase subunit of a proteasome-like degradation complex; this subunit has chaperone activity. The binding of ATP and its subsequent hydrolysis by HslU are essential for unfolding of protein substrates subsequently hydrolyzed by HslV. HslU recognizes the N-terminal part of its protein substrates and unfolds these before they are guided to HslV for hydrolysis.

Proteolytic subunit of ClpA-ClpP and ClpX-ClpP ATP-dependent serine proteases; Cleaves peptides in various proteins in a process that requires ATP hydrolysis. Has a chymotrypsin-like activity. Plays a major role in the degradation of misfolded proteins. May play the role of a master protease which is attracted to different substrates by different specificity factors such as ClpA or ClpX. Participates in the final steps of RseA-sigma-E degradation, liberating sigma-E to induce the extracytoplasmic-stress response. Degrades antitoxin MazE.

Peptidase component of the HslUV protease; Protease subunit of a proteasome-like degradation complex believed to be a general protein degrading machinery. The complex has been shown to be involved in the specific degradation of heat shock induced transcription factors such as RpoH and SulA. In addition, small hydrophobic peptides are also hydrolyzed by HslV. HslV has weak protease activity even in the absence of HslU, but this activity is induced more than 100-fold in the presence of HslU. HslU recognizes protein substrates and unfolds these before guiding them to HslV for hydrolysis. [...]

Peptidyl-prolyl cis/trans isomerase (trigger factor); Involved in protein export. Acts as a chaperone by maintaining the newly synthesized secretory and non-secretory proteins in an open conformation. Binds to 3 regions of unfolded substrate PhoA, preferring aromatic and hydrophobic residues, keeping it stretched out and unable to form aggregates. Binds to nascent polypeptide chains via ribosomal protein L23. Functions as a peptidyl-prolyl cis-trans isomerase in vitro, this activity is dispensible in vivo for chaperone activity. Belongs to the FKBP-type PPIase family. Tig subfamily.