9ftw

Publication Abstract from PubMed

Ribonucleases (RNases) are ubiquitous enzymes that process or degrade RNA, essential for cellular functions and immune responses. The EndoU-like superfamily includes endoribonucleases conserved across bacteria, eukaryotes, and certain viruses, with an ancient evolutionary link to the ribonuclease A-like superfamily. Both bacterial EndoU and animal RNase A share a similar fold and function independently of cofactors. In contrast, the eukaryotic EndoU catalytic domain requires divalent metal ions for catalysis, possibly due to an N-terminal extension near the catalytic core. In this study, we used biophysical and computational techniques along with in vitro assays to investigate the calcium-dependent activation of human EndoU. We determined the crystal structure of EndoU bound to calcium and found that calcium binding remote from the catalytic triad triggers water-mediated intramolecular signaling and structural changes, activating the enzyme through allostery. Calcium-binding involves residues from both the catalytic core and the N-terminal extension, indicating that the N-terminal extension interacts with the catalytic core to modulate activity in response to calcium. Our findings suggest that similar mechanisms may be present across all eukaryotic EndoUs, highlighting a unique evolutionary adaptation that connects endoribonuclease activity to cellular signaling in eukaryotes.

Molecular Basis for the Calcium-Dependent Activation of the Ribonuclease EndoU.,Malard F, Dias K, Baudy M, Thore S, Vialet B, Barthelemy P, Fribourg S, Karginov FV, Campagne S Res Sq [Preprint]. 2024 Jul 15:rs.3.rs-4654759. doi: 10.21203/rs.3.rs-4654759/v1. PMID:39070628^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.