Nonalcoholic steatohepatitis (NASH) is a global health concern with no effective treatment options. Apoptosis-signaling kinase 1 (ASK1) hyperactivity induced by oxidative stress has been identified as a key contributor to hepatic inflammation, apoptosis, and liver fibrogenesis, is the hallmark of NASH. Several attempts by companies and academia have attempted to develop ASK1 inhibitors, however, they failed in clinical trials due to substantial side effects. Hence, there is an unmet need for an alternate approach such as protein-protein interactions (PPIs) to modulate ASK1 activity via allosteric regulators rather than complete blockage of ASK1. The PPI driven allosteric inhibition of ASK1 traverses a promising strategy as its regulators in disease states are well documented. Among them, 14-3-3, a -ve regulator that allosterically inhibits ASK1 as it restricts the access of the catalytic site by preventing the substrate from entering into the catalytic site, however the mechanistic insights have not been explored. The 14-3-3 binding site and its impact at catalysis site is wired through an unstructured region indicating the possibility that this process is highly dynamics coupled, a major bottleneck in PPI-based inhibitor designing. Therefore, we are investigating the structural behavior of 14-3-3 and ASK1 interfaces using molecular modeling and microsecond molecular dynamics simulations. We identified that dynamics which correlate the structural and functional implications of the allosteric modulation via 14-3-3 on ASK1’s catalytic site and underscores a novel strategy for allosteric inhibition of ASK1. Extensive molecular dynamics simulations revealed that the complex state of ASK1 (with 14-3-3) was more stable than the apo state with a more restricted catalytic pocket volume as it visualizes that it potentially prevents the substrate entry in the absence of a ligand. Our findings provide structural determinants of allosteric regulation of ASK1 by 14-3-3 for the development of novel therapeutics against ASK1.

The development of potent non-nucleoside inhibitors (NNIs) could be an alternate strategy to combating infectious bovine viral diarrhea virus (BVDV), other than the traditional vaccination. RNA-dependent RNA polymerase (RdRp) is an essential enzyme for viral replication; therefore, it is one of the primary targets for countermeasures against infectious diseases. The reported NNIs, belonging to the classes of quinolines (2h: imidazo[4,5-g]quinolines and 5m: pyrido[2,3-g] quinoxalines), displayed activity in cell-based and enzyme-based assays. Nevertheless, the RdRp binding site and microscopic mechanistic action are still elusive, and can be explored at a molecular level. Here, we employed a varied computational arsenal, including conventional and accelerated methods, to identify quinoline compounds’ most likely binding sites. Our study revealed A392 and I261 as the mutations that can render RdRp resistant against quinoline compounds. In particular, for ligand 2h, mutation of A392E is the most probable mutation. The loop L1 and linker of the fingertip is recognized as a pivotal structural determinant for the stability and escape of quinoline compounds. Overall, this work demonstrates that the quinoline inhibitors bind at the template entrance channel, which is governed by conformational dynamics of interactions with loops and linker residues, and reveals structural and mechanistic insights into inhibition phenomena, for the discovery of improved antivirals.