Biology subjects

Pisliakov, A. V.

Publications and source records attributed to Pisliakov, A. V..

3 recordsLinked to original sources

bioRxiv2020

Identification of novel RNA Polymerase II CTD interaction sites on the mRNA Capping Enzyme

1Recruitment of the mRNA Capping Enzyme (CE/RNGTT) to the site of transcription is essential for the formation of the 5 mRNA cap, which in turn ensures efficient transcription, splicing, polyadenylation, nuclear export and translation of mRNA in eukaryotic cells. The CE is recruited and activated by the Serine-5 phosphorylated carboxyl-terminal domain (CTD) of RNA polymerase II. Through the use of molecular dynamics simulations and enhanced sampling techniques, we provide a systematic and detailed characterisation of the human CE-CTD interface, describing the effect of the CTD phosphorylation state, length and orientation on this interaction. Our computational analyses identify novel CTD interaction sites on the human CE surface and quantify their relative contributions to CTD binding. We also identify differences in the CTD binding conformation when phosphorylated at either the Serine-2 or Serine-5 positions, thus providing insights into how the CE reads the CTD code. The computational findings are then validated by binding and activity assays. These novel CTD interaction sites are compared with cocrystal structures of the CE-CTD complex in different eukaryotic taxa, leading to the conclusion that this interface is considerably more conserved than previous structures have indicated.

biophysics↗

bioRxiv2019

Mechanism of allosteric activation of human mRNA cap methyltransferase (RNMT) by RAM: Insights from accelerated molecular dynamics simulations

The RNA guanine-7 methyltransferase (RNMT) in complex with RNMT-Activating Miniprotein (RAM) catalyses the formation of a N7-methylated guanosine cap structure on the 5 end of nascent RNA polymerase II transcripts. The mRNA cap protects the transcript from exonucleases and recruits cap-binding complexes that mediate RNA processing, export and translation. By using microsecond standard and accelerated molecular dynamics simulations, we provide for the first time a detailed molecular mechanism of allosteric regulation of RNMT by RAM. We show that RAM selects the RNMT active site conformations that are optimal for binding of substrates (AdoMet and the cap), thus enhancing their affinity. Furthermore, our results strongly suggest the likely scenario in which the cap binding promotes the subsequent AdoMet binding, consistent with the previously suggested cooperative binding model. By employing the dynamic network and community analyses, we revealed the underlying long-range allosteric networks and paths that are crucial for allosteric regulation by RAM. Our findings complement and explain previous experimental data on RNMT activity. Moreover, this study provides the most complete description of the cap and AdoMet binding poses and interactions within the enzymes active site. This information is critical for the drug discovery efforts that consider RNMT as a promising anti-cancer target.

biophysics↗

bioRxiv2017

Intracellular Passage Of Na+ In An Active State G Protein Coupled Receptor

Playing a central role in cell signalling, GPCRs have evolved into the largest superfamily of membrane proteins and form the majority of drug targets in humans. How extracellular agonist binding triggers the activation of GPCRs and associated intracellular effector proteins remains, however, poorly understood. High resolution structural studies have recently revealed that inactive class-A GPCRs harbour a conserved binding site for Na+ ions in the centre of their transmembrane domain, accessible from the extracellular space. Here, we show that the opening of a conserved hydrated channel in the activated state receptors allows the Na+ ion to egress from its binding site into the cytosol. Coupled with protonation changes, this ion movement occurs without significant energy barriers, and can be driven by physiological transmembrane ion and voltage gradients. We propose that Na+ ion exchange with the cytosol is a key step in GPCR activation, which locks receptors in long-lived active-state conformations.

biophysics↗