Science is a subject that you need not learn specifically. It is all around you and all you need is to observe it closely. That is what I do. OBSERVE. After a post-graduation in Biotechnology, I decided to continue my career in research and innovations. Therefore I have joined the National Institute of Immunology and BITS-Pilani Hyderabad for my Ph.D. research. I have worked on several projects during my Ph.D. and postdoctoral research and this helped to understand various dimensions of microbiology, genetic engineering, metabolomics, molecular biology, drug target identification, drug screening, drug development, in vivo drug testing and identification of metabolic bio-signature (Biomarkers) for better diagnosis and therapeutic interventions.
For my Ph.D. research, I was involved in investigating and establishing GlmUMtb and UDP-GlcNAc biosynthesis pathway as a candidate for intervention measures against established tuberculosis infections. GlmUMtb is a bi-functional enzyme engaged in the synthesis of two metabolic intermediates N-acetylglucosamine-1-phosphate (GlcNAc-1-P) and UDP-GlcNAc, catalyzed by the C- and N-terminal domains respectively. UDP-GlcNAc is a key metabolite essential for the synthesis of peptidoglycan, disaccharide linker, arabinogalactan, and mycothiols. During five and half years of my doctoral studies, I was involved in the structure and functional analysis of GlmUMtb and determined the detailed catalytic mechanism of acetyltransferase activity and phosphorylation site. In 2012, this collaborative effort with Dr. Balaji Prakash’s group was published in J. Biological Chemistry, in which I was the co-first author.
My Ph.D. work in one diagram.
Further, to do biological validation of GlmUMtb as a potential drug target, we have generated a conditional gene deletion mutant of GlmUMtb. We found that the absence of GlmUMtb leads to extensive perturbation of bacterial morphology and a substantial reduction in cell wall thickness under normoxic as well as hypoxic conditions. Complementation studies showed that both acetyl- and uridyltransferase activities of GlmUMtb were independently essential for bacterial survival in vitro, and GlmUMtb was also found to be essential for mycobacterial survival in THP-1 cells as well as during infection in guinea pigs. Depletion of GlmUMtb from infected murine lungs, four weeks post-infection, led to a significant reduction in the bacillary load.
Next, after screening two different generations of inhibitors against GlmUMtb, we found one novel allosteric inhibitor (Oxa33) targeting uridyltransferase activity. With the help of MD simulation and mutational studies, we confirmed the binding site. Also, the overexpression of GlmUMtb increases the MIC value, which establishes the specificity of Oxa33 to GlmUMtb. The administration of Oxa33 to infected mice resulted in a significant decrease in the bacillary load. Our study established GlmUMtb as a strong candidate for intervention measures against established tuberculosis infections. The study also demonstrated that GlmUMtb is a promising target for therapeutic intervention and Oxa33 can be pursued as a lead molecule. This work was recently published in PLoS Pathogens.
Right after Ph.D. I joined Weill Cornell Medicine, New York, U.S.A. as a postdoctoral researcher and started working in the field of metabolomics of Mycobacterium tuberculosis and antibiotic development. My goal is to find out various biosignatures and their applications to enhance the efficacy of the antibiotics. As metabolism is the key player and target of any therapeutic agent, therefore it would be really interesting to decipher the role of drug metabolism in TB.