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Publication Abstract from PubMed

Ro60 is a conserved RNA-binding protein essential for RNA quality control and implicated in autoimmune responses. In this study, we present the structural and functional characterization of phiRo60, an Ro60 homolog from Thermus phage phiLo, with its crystal structure determined at 1.99 A. Despite limited sequence identity with bacterial and amphibian homologs, phiRo60 maintains the canonical doughnut-shaped architecture comprising HEAT repeats and a von Willebrand factor A domain. Surface electrostatic analysis reveals an extensive positively charged region across multiple alpha-helices, likely facilitating diverse RNA interactions. Moreover, phiRo60 binds two Y RNA-like molecules (Yrl1 and Yrl2), identified from the phiLo genome, with distinct stoichiometries, leading to the formation of higher-order nucleocytoplasmic ribonucleoprotein (RNP) complexes. Cryo-electron microscopy of phiRo60-Yrl2 RNP complexes revealed a minor population adopting a dimeric assembly, and key positively charged residues are important for phiRo60-Yrl2 interactions. Additionally, phiRo60 and Yrls interact with host Thermus thermophilus HB8 polynucleotide phosphorylase (PNPase), forming tripartite RYPER-like complexes and attenuating the ribonuclease activity of PNPase. These findings highlight phiRo60 as a structurally adaptable Ro60 homolog capable of diverse RNA interactions and host factor recruitment, implying unique strategies for phages to counteract host defense systems in thermophilic environments.

Structural and molecular mechanisms of an Ro60 homolog from a Thermus bacteriophage.,Hu Z, Jin Z, Guo L, Zeng L, Dong X, Jiang L, Dai W, Ma J, Huang Y Nucleic Acids Res. 2025 May 22;53(10):gkaf470. doi: 10.1093/nar/gkaf470. PMID:40464688^[1]

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