Date & Time: 30th August 2023 (Wednesday), 5:30 p.m. to 6:30 p.m.
Venue: C V Raman Hall, IISER Tirupati Transit Campus
Title: Understanding Biological Molecular Machines-Order, Intrinsic Disorder and Allosteric Determinants
Speaker: Prof Balasubramanian Gopal,
Professor, Division of Biological Sciences,
Indian Institute of Science, Bengaluru
Form, in context, defines function. This, we contend, is particularly relevant in the context of understanding the catalytic activity of an enzyme and its regulation. Here, we describe two examples to illustrate this aspect of biomolecules. The first is the case of the High-temperature requirement A- an enzyme that is allosterically regulated. An effector binding to the PDZ domain modulates proteolytic activity. We describe the inter-residue interaction networks identified first by molecular dynamics simulations. Further, this information was used to engineer mutations that could potentially perturb allostery in Mycobacterium tuberculosis HtrA. Electron density from data collected on cryo-protected HtrA crystals revealed that mutations altered the topology of the active site. Ensemble models fitted into electron density calculated from room temperature diffraction data showed that only a fraction of these models had a catalytically competent active site conformation alongside a functional oxyanion hole thus providing experimental evidence that these mutations influenced conformational sampling. The second illustrative example is that of the M. tuberculosis RNA polymerase holo-complex. Rapid re-engineering of the transcription profile in response to environmental stimuli is achieved by multiple initiation factors- Extra cytoplasmic Function σ factors- that confer promoter selectivity to the RNA polymerase holoenzyme. Structural studies of the Mycobacterial RNA polymerase transcription initiation complex provide a framework to experimentally validate specific functional hypotheses that were hitherto unclear in terms of the disordered linkers and flexible loops that were poorly conserved. We present data to demonstrate the role of these disordered polypeptides.
About the speaker:
- Gopal is a Professor at the Division of Biological Sciences, Indian Institute of Science, Bengaluru. An alumnus of the Maharashtra Education Society, Pune, Indian Institute of Technology, Kanpur and Indian Institute of Science, Bengaluru, he is structural biologist by training. His current research interests include gene expression analysis and synthetic microbiology. In addition to his academic affiliation, he is associated either as a co-founder, advisor or consultant to start-up and mid-size biotechnology and pharmaceutical industries involved in the production of biosimilars and active pharmaceutical ingredients. He is a fellow of all three science academies in India and a recipient of the Shanti Swaroop Bhatnagar prize awarded by the Council for Scientific and Industrial Research, Government of India.