Biophysical Society Thematic Meeting | Trieste 2024

Emerging Theoretical Approaches to Complement Single-Particle Cryo-EM

Poster Abstracts

23-POS Board 23 MOLECULAR MECHANISM OF ZINC-CATALYZED COVALENT SPLICING MODULATION Riccardo Rozza 1 ; Angela Parise 1 ; Jana Aupic 1 ; Angelo Spinello 2 ; Alessandra Magistrato 1 ; The pre-messenger RNA (pre-mRNA) splicing process is catalyzed by the spliceosome, an intricate biochemical machinery comprising hundreds of proteins and five small nuclear RNAs (snRNAs). Pre-mRNA splicing consists of joining the coding regions (e.g., removing non-coding ones (introns) to form protein-coding and long-coding RNAs. Faithful recognition of key signaling sequences is key for splicing fidelity and the onset of diseases [1]. The heptameric SF3b complex, a component of the spliceosome, plays a crucial role in the early stages of splicing by recognizing the branch point sequence. SF3b is also the target of known splicing modulators [2]. Of particular interest is the Spliceostatin A (SSA) that has been recently demonstrated in cryo-EM studies to covalently bind to cysteine of a zinc finger of PHF5A (a core SF3b complex component) and strongly interferes with intron-exon recognition in cancer cells. In this study we shed light on the reaction mechanism of SSA covalent binding to PHF5A by means of classical and quantum molecular dynamics simulations. We identify the peculiar features that lead to SSA covalent binding to PHF5A as well as the chemical-physical characteristics exploitable for efficiently targeting the SF3b complex with SSA-like drugs. [1] Rozza, R., Janoš, P., Spinello, A., & Magistrato, A. (2022). Role of computational and structural biology in the development of small-molecule modulators of the spliceosome. Expert Opinion on Drug Discovery, 17(10), 1095-1109. [2] Cretu, C., Gee, P., Liu, X., Agrawal, A., Nguyen, T. V., Ghosh, A. K., ... & Pena, V. (2021). Structural basis of intron selection by U2 snRNP in the presence of covalent inhibitors. Nature Communications, 12(1), 4491. 1 CNR-IOM c/o SISSA, Trieste, Italy 2 Univeristy of Palermo, Palermo, Italy

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