Ranganathan, S. V. | bioRxiv Science

bioRxiv2022

In silico screening and testing of FDA approved small molecules to block SARS-CoV-2 entry to the host cell by inhibiting Spike protein cleavage

The COVID-19 pandemic began in 2019, but it is still active. The development of an effective vaccine reduced the number of deaths; however, a treatment is still needed. Here, we aimed to inhibit viral entry to the host cell by inhibiting Spike (S) protein cleavage by several proteases. We develop a computational pipeline to repurpose FDA-approved drugs to inhibit protease activity and thus prevent S protein cleavage. We tested some of our drug candidates and demonstrated a decrease in protease activity. We believe our pipeline will be beneficial in identifying a drug regimen for COVID-19 patients.

biophysics↗

bioRxiv2020

Base Pairing and Functional Insights into N3-methylcytidine (m3C) in RNA

N3-methylcytidine (m3C) is present in both eukaryotic tRNA and mRNA and plays critical roles in many biological processes. We report the synthesis of the m3C phosphoramidite building block and its containing RNA oligonucleotides. The base-pairing stability and specificity studies show that the m3C modification significantly disrupts the stability of the Watson-Crick C:G pair. Further m3C decreases the base pairing discrimination between C:G and the other mismatched C:A, C:U, and C:C pairs. Our molecular dynamic simulation study further reveals the detailed structural insights into the m3C:G base pairing pattern in an RNA duplex. More importantly, the biochemical investigation of m3C using reverse transcription shows that N3-methylation specifies the C:A pair and induces a G to A mutation using HIV-1-RT, MMLV-RT and MutiScribe-RT enzymes, all with relatively low replication fidelity. For other reverse transcriptases with higher fidelity like AMV-RT, the methylation could completely shut down DNA synthesis.

biochemistry↗