Functional Analysis of Promoter of Cus Operon: Activity of Copper-mediated Induction of Cus Operon Promoter in E. Coli.

Copper is an essential trace metal for both prokaryotes and eukaryotes, and is associated with various metal enzymes which play many essential roles in the living system. But excess of the metal is very toxic and even lethal for living organisms. In microorganisms the intracellular level of copper is maintained by many genes working as an operon and induced by the presence of copper in their environment. One such operon is called cus operon regulated by cusRS two component system in Klebsiella pneumoniae. This cusS (sensory region) and cusR (regulatory region) autoregulate the expression of structural as well as regulatory part of the cus operon by binding of CusR protein to the bidirectional promoter part of the operon. The functional analysis showed that the cloned promoter was highly sensitive to copper metal concentrations and follows Michaelis Menton kinetics at very high concentrations. Additionally, cusRS promoter was also scanned for various transcriptional factor binding sites like -10, -35 boxes for binding of RNA polymerase. Similarly, CusR binding region was highlighted after docking of CusR protein on promoter sequence via Hex Dock software.