Biology

Prof. Jayadeva Bhat
IIT Mumbai

Abstract:

Allostery plays a key role in many biological processes.  Our understanding of the mechanism of allostery has been evolving ever since the original  models  of allostery were  proposed. It is now generally believed that allostery manifests because of the population shift (or conformational selection) occurring in response to the interaction with the ligand. I shall focus on allostery exhibited by two paralogs(Gal3p and Gal1p), which function as signal transducers  of the GAL genetic switch of Saccharomyces cerevisaie. Gal3p, a monomeric allosteric protein turns ON  the GAL switch in response to  galactose  and ATP. Gal1p also carries out the above function in addition to phosphorylating galactose to galactose-1-phosphate. That is,  Gal1p is a bifunctional protein: an enzyme as well as a signal transducer. First part of the talk would focus on our attempts at providing a missing evidence in support of the conformation selection model of allostery,  using Gal3p as a paradigm.  In the second half, I shall focus on our struggle to figure out how Gal1p  functions as an enzyme as well as an allosteric signal transducer in response to the same set of substrates/ligands-galactose and ATP.