Biology subjects

Trivedi, D. V.

Publications and source records attributed to Trivedi, D. V..

4 recordsLinked to original sources

bioRxiv2022

A small-molecule myosin inhibitor as a targeted multi-stage antimalarial

Malaria is a devastating disease that resulted in an estimated 627,000 deaths in 2020. About 80% of those deaths were among children under the age of five. Our approach is to develop small molecule inhibitors against cytoskeletal targets that are vital components of parasite function, essential at multiple stages of parasite infection, can be targeted with high specificity, and are highly druggable. Here we describe KNX-115, which inhibits purified Plasmodium falciparum myosin A (PfMyoA) actin-activated ATPase with a potency in the 10s of nanomolar range and >50-fold selectivity against cardiac, skeletal, and smooth muscle myosins. KNX-115 inhibits the blood and liver stages of Plasmodium with an EC50 of about 100 nanomolar, with negligible liver cell toxicity. In addition, KNX-115 inhibits sporozoite cell traversal and blocks the gametocyte to oocyst conversion in the mosquito. KNX-115 displays a similar killing profile to pyrimethamine and parasites are totally killed after 96 hours of treatment. In line with its novel mechanism of action, KNX-115 is equally effective at inhibiting a panel of Plasmodium strains resistant to experimental and marketed antimalarials. In vitro evolution data likely suggests a refractory potential of KNX-115 in developing parasite resistance.

pharmacology and toxicology↗

bioRxiv2019

The molecular basis of hypercontractility caused by the hypertrophic cardiomyopathy mutations R403Q and R663H

Hypertrophic cardiomyopathy (HCM) mutations in {beta}-cardiac myosin and myosin binding protein-C (MyBP-C) cause hypercontractility of the heart. We show that hypercontractility caused by the HCM myosin mutation R663H cannot be explained by changes in the fundamental parameters such as actin-activated ATPase, intrinsic force, velocity of pure actin or regulated thin filaments, or the pCa50 of the velocity of regulated thin filaments. The same conclusion was made earlier for the HCM myosin mutation R403Q (Nag et al. 2015). Using enzymatic assays for the number of functionally-available heads in purified human {beta}-cardiac myosin preparations, we provide evidence that both R403Q and R663H HCM myosin mutations cause hypercontractility by increasing the number of functionally-accessible myosin heads. We also demonstrate that the myosin mutation R403Q, but not R663H, ablates the binding of myosin with the C0-C7 fragment of myosin binding protein-C.

biochemistry↗

bioRxiv2019

Hypertrophic cardiomyopathy mutations at the folded-back sequestered β-cardiac myosin S1-S2 and S1-S1 interfaces release sequestered heads and increase myosin enzymatic activity

Hypertrophic cardiomyopathy (HCM) affects 1 in 500 people and leads to hyper-contractility of the heart. Nearly 40 percent of HCM-causing mutations are found in human {beta}-cardiac myosin. Previous studies looking at the effect of HCM mutations on the force, velocity and ATPase activity of the catalytic domain of human {beta}-cardiac myosin have not shown clear trends leading to hypercontractility at the molecular scale. Here we present functional data showing that four separate HCM mutations located at the myosin head-tail (R249Q, H251N) and head-head (D382Y, R719W) interfaces of a folded-back sequestered state referred to as the interacting heads motif lead to a significant increase in the number of heads functionally accessible for interaction with actin. These results provide evidence that HCM mutations can modulate myosin activity by disrupting intramolecular interactions within the proposed sequestered state, thereby leading to hypercontractility at the molecular level.

biochemistry↗

bioRxiv2018

Mavacamten stabilizes a folded-back sequestered super-relaxed state of β-cardiac myosin

SummaryMutations in {beta}-cardiac myosin, the predominant motor protein for human heart contraction, can alter power output and cause cardiomyopathy. However, measurements of the intrinsic force, velocity and ATPase activityof myosin have not provided a consistent mechanism to link mutations to muscle pathology. An alternative modelpositsthat mutations in myosin affect the stability ofa sequestered, super-relaxed state (SRX) of the proteinwith very slow ATP hydrolysis and thereby change the number of myosin heads accessible to actin. Here, using a combination of biochemical and structural approaches, we show that purified myosin enters aSRX thatcorresponds to a folded-back conformation, which in muscle fibersresults insequestration of heads around the thick filament backbone. Mutations that cause HCM destabilize this state, while the small molecule mavacamtenpromotes it. These findings provide a biochemical and structural link between the genetics and physiology ofcardiomyopathywith implications for therapeutic strategies.

biochemistry↗