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Narwal, M.

Publications and source records attributed to Narwal, M..

2 recordsLinked to original sources

Plasmodium falciparum aquaglyceroporin (PfAQP) orchestrates glycerol-dependent lipid metabolism, membrane biogenesis, metabolomic flux, parasite growth and stress adaptation

Aquaglyceroporins (AQPs) are integral membrane channel proteins that facilitate transport of water and other solutes such as glycerol, thereby playing vital roles in cellular homeostasis. Here, we functionally characterized Plasmodium falciparum aquaglyceroporin (PfAQP) through localization, inducible knockdown, and comprehensive metabolomic analyses revealing its key role in lipid homeostasis and metabolomic flux. PfAQP localizes to the parasite plasma membrane and food vacuole membrane, at critical interfaces for nutrient and metabolite exchange. A glmS-ribozyme mediated inducible knock-down of PfAQP severely impairs parasite development from trophozoite to schizont, leading to marked suppression in parasite growth. Ultra-Expansion Microscopy (UExM) analyses show profound defects in membrane biogenesis, along with disruption in cytokinesis under PfAQP knock-down conditions. Detailed lipidomic analyses suggests that PfAQP disruption cause altered lipid homeostasis, characterized by reduced membrane phospholipid biosynthesis, impaired lipid scavenging, and accumulation of storage lipids. Metabolomic analyses further indicate metabolic dysregulation characterized by reduction in amino acid levels and dysregulated mitochondrial metabolism, including impaired tricarboxylic acid (TCA) cycle. Strikingly, PfAQP expression gets transiently upregulated under nutrient starvation condition, and its ablation drastically compromise parasite recovery, highlighting its role in adaptive responses. Overall, these results establish PfAQP as a critical regulator of glycerol-dependent metabolic pathways, orchestrating membrane biogenesis, energy metabolism, and stress resilience--functions indispensable for parasite growth and survival.

microbiology↗

SARS-CoV-2 polyprotein substrate regulates the stepwise Mpro cleavage reaction

Processing of polyproteins pp1a and pp1ab in Coronaviruses by main protease Mpro is a crucial event in virus replication and a promising target for antiviral drug development. Mpro recognizes multiple recognition sites within polyproteins in a defined order, but its mechanism remains enigmatic due to lack of structural information of the polyprotein substrate bound Mpro complex. Here, we present the cryo-EM structures of the SARS-CoV-2 Mpro in an apo-form and in complex with the nsp7-10 region of pp1a polyprotein. The structure shows that the interaction of Mpro with polyproteins is limited to the recognition site connecting nsp9 and nsp10 proteins without any tight association with the rest of polyprotein structure or sequence. Comparison between the apo-form and the polyprotein bound structures of Mpro highlights the flexible nature of active site region allowing the Mpro to accommodate various recognition sites connecting series of nsp proteins. These observations suggest that the role of Mpro for selecting a preferred cleavage site within the polyprotein is limited and underscore the structure, conformation and/or dynamics of polyprotein determining the sequential polyprotein cleavage by Mpro.

biophysics↗