nucleotide-binding domain (NBD) of Escherichia coli chaperone protein HscC and similar proteins
Escherichia coli HscC, also called Hsc62, or YbeW, may act as the chaperone. It has ATPase activity. It cannot be stimulated by DnaJ. Members in this subfamily belong to the heat shock protein 70 (Hsp70) family of chaperones that assist in protein folding and assembly and can direct incompetent "client" proteins towards degradation. Typically, Hsp70s have a nucleotide-binding domain (NBD) and a substrate-binding domain (SBD). The nucleotide sits in a deep cleft formed between the two lobes of the NBD. The two subdomains of each lobe change conformation between ATP-bound, ADP-bound, and nucleotide-free states. ATP binding opens up the substrate-binding site; substrate-binding increases the rate of ATP hydrolysis. Hsp70 chaperone activity is regulated by various co-chaperones: J-domain proteins and nucleotide exchange factors (NEFs). Two genes in the vicinity of the HscC gene code for potential cochaperones: J-domain containing proteins, DjlB/YbeS and DjlC/YbeV. HscC and its co-chaperone partners may play a role in the SOS DNA damage response. HscC does not appear to require a NEF.
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