Biology subjects

Pipito, L.

Publications and source records attributed to Pipito, L..

4 recordsLinked to original sources

bioRxiv2026

Deacylation of SNAP25 protein family isoforms reveals distinct substrate selectivities of α/β hydrolase domain (ABHD) deacylases

Reversible S-acylation controls protein trafficking, localisation and activity within cells, yet the limited understanding of the regulatory mechanisms of S-acylation/deacylation cycles represents one of the biggest obstacles in exploiting this prevalent post-translational modification for therapeutic purposes. Here, we identified ABHD13 and ABHD16A as novel deacylases regulating the SNAP25 family of SNARE proteins responsible for vesicular membrane fusion. We determined the mechanism and structural determinants for ABHD13-mediated deacylation and substrate selectivity towards SNAP25b, and identified a novel mechanism of acyl chain extraction for integral membrane deacylases. This is the first report of deacylase selectivity mapped to a single amino acid position in full-length proteins.

molecular biology↗

bioRxiv2022

Hidden GPCR structural transitions addressed by multiple walker supervised molecular dynamics (mwSuMD)

The structural basis for the pharmacology of G protein-coupled receptors (GPCRs), the most abundant membrane proteins and the target of about 35% of approved drugs, is still a matter of intense study. What makes GPCRs challenging to study is the inherent flexibility and the metastable nature of interaction with extra-and intracellular partners that drive their effects. Here, we present a molecular dynamics (MD) adaptive sampling algorithm, namely multiple walker supervised molecular dynamics (mwSuMD), to address complex structural transitions involving GPCRs without energy input. We first report the binding and unbinding of the vasopressin peptide from its receptor V2. Successively, we present the complete transition of the glucagon-like peptide-1 receptor (GLP-1R) from inactive to active, agonist and Gs-bound state, and the GDP release from Gs. To our knowledge, this is the first time the whole sequence of events leading from an inactive GPCR to the GDP release is simulated without any energy bias. We demonstrate that mwSuMD can address complex binding processes intrinsically linked to protein dynamics out of reach of classic MD.

bioinformatics↗

bioRxiv2022

Is The Stalk of the SARS-CoV-2 Spike Protein Druggable?

The SARS-CoV-2 virus spike protein (SP) is the vector of the virus infectivity. The high propensity to mutate in key regions responsible for the recognition of the human angiotensinconverting enzyme 2 (hACE2) or the antibodies produced by the immune system following infection or vaccination makes subunit 1 of the SP a difficult to target and, to date, efforts have not delivered any ACE2 binding inhibitor yet. The inherent flexibility of the stalk region, within subunit S2, is key to SARS-CoV-2 high infectivity because it facilitates the receptor binding domain encounter with ACE2. Thus, it could be a valuable therapeutic target. By employing a fragment-based strategy, we computationally studied the druggability of the conserved part of the SP stalk by means of an integrated approach that combines molecular docking with high-throughput molecular dynamics simulations. Our results suggest that the druggability of the stalk is challenging and provide the structural basis for such difficulty.

bioinformatics↗

bioRxiv2022

Understanding The Role of Heparinoids on the SARS-CoV-2 Spike Protein through Molecular Dynamics Simulations

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to pose a threat, with an estimated number of deaths exceeding 5 million. SARS-CoV-2 entry into the cell is mediated by its transmembrane spike glycoprotein (S protein), and the angiotensin-converting enzyme 2 (ACE2) receptor on the human cell surface. The extracellular heparan sulphate (EcHS) enhances the S protein binding through a mechanism that is still unknown. Surprisingly, low molecular weight heparin (LMWH) and HS in the disaccharide form (dHS) hinder the S protein binding to ACE2, despite the similarity with EcHS. We investigated the molecular mechanism behind this inhibition through molecular dynamics (MD) simulations to understand the interaction pattern of the heparinoids with S protein and ACE2 receptor.

bioinformatics↗