Mycobacterium tuberculosis ClpC1

Chaperone proteins are vital proteins required by many bacteria during normal growth and also under conditions of severe stress to maintain cell viability. Chaperone proteins assist in the proper refolding of proteins or the assembly of proteases that process proteins that cannot be altered conformationally [1,2]. Heat shock proteins act as chaperones and interact with hydrophobic residues exposed in unfolded polypeptides to facilitate their correct folding, prevent protein aggregation and translocate them across cell membranes [3]. Increased expression of heat shock proteins is triggered by a range of stress conditions, and is also induced in both the host and pathogen during the process of infection [4]. Heat shock protein, HSP100 or caseinolytic protein (Clp) is a highly conserved family of molecular chaperones, and members of this family have been shown to exist in a variety of organisms from Escherichia coli to humans [5–11]. Clp family members possess ATPase activity and have been grouped as Class I or II based on the presence of two or one highly conserved nucleotide-binding regions [12]. Class I proteins, ClpA–E and L, all have two distinct nucleotide-binding domains (NBDs) or AAA+ modules, whereas Class II proteins,