Tapan K. Misra

Associate Professor

Ph.D., University of Calcutta, India

Room: E616 MSB, Tel: 312-996-9609

Email: tmisra@uic.edu

Molecular pathogenesis and bacterial gene regulations

My laboratory has been engaged in the studies of the different mechanisms of regulation of gene expression in bacteria. In two separate projects, we have focused on learning how toxin gene expression is regulated in Staphylococcus aureus and how the expression of mercury, zinc and cobalt resistance genes are modulated when resistant bacteria encounter the metallic or organometallic toxic compounds.

Although most of the S. aureus infections are localized in the skin and underlying tissues, highly invasive strains can overcome the local phagocytic systems, spread through the bloodstream and infect almost any tissue including that of the heart, causing life-threatening endocarditis. In addition, some strains of S. aureus and S. epidermidis can colonize on biomaterials used for surgical implants. Recent findings of multiple drug resistant strains (resistant against all drugs currently in use) in hospitals have heightened the need for exploring new methods to combat infections caused by S. aureus. There are global regulators (agr, sar) which control the transcription of a wide variety of unlinked genes, many of which are considered to be involved in pathogenesis. An understanding of the mechanisms of regulation of expression of virulence factors may lead to the identification of target sites for the development of therapeutic agents.

The purification of active RNA polymerase, and characterization of the primary transcription factor s and an alternative s factor from S. aureus were reported for the first time by my laboratory. Our studies elucidate some of the roles of these s factors in transcription from several promoters of the global regulatory elements, agr and sar. Our broad-range goal is to understand how virulence gene expression in S. aureus is controlled by the different regulatory elements encoded by the global regulatory loci in concert with the RNA polymerase containing different s factors.

In a separate project, we have characterized novel metallic and organometallic receptor proteins regulating the expression of the mercury, zinc and cobalt resistance operons.