(A) Study of monomeric actin dynamics and its effect on actin filament assembly and cardiovascular diseases. Defects in structure and dynamics of actin are causative in many cardiovascular diseases. Fundamental to the function of actin is its cycling between a monomeric globular G-state and a filamentous, F state. In vivo, the transition between the G- and F-states is strongly controlled by the state of the bound adenine nucleotide. My research is focused on quantifying the dynamics of G-actin in different nucleotide states and determining the role of dynamics in F-actin assembly and heart diseases. Using an array of NMR techniques (CPMG, CEST, RDC etc.) in combination with other biophysical techniques and mutagenesis, we have been trying to address long-standing, important questions regarding how the dynamics of G-actin affects biochemical functions and how the dynamics of G-actin are perturbed by disease- causing mutations. These investigations will provide a unique mechanistic understanding of actin that has not been available through previous crystallographic and other physical analyses.
(B) Understanding the structural basis of LLPS and its role in bimolecular condensate formation. Liquid-liquid phase separation (LLPS) driven by multivalent interactions is believed to underlie formation of biomolecular condensates, membrane-less cellular compartments that concentrate macromolecules. One such condensate, PML nuclear bodies (NBs), are dynamic sub-nuclear structures of 0.2–1.0 mm present in most mammalian cell nuclei. The PML protein has been shown to be essential for the formation of the PML-NBs. I am interested in understanding the structural basis of multivalent interactions among PML and other proteins that leads to formation of PML-NBs. I am also interested in deciphering the dynamics of PML that controls the post-translational modifications and hence recruitment of different client molecules to the scaffold.