Structural and evolutionary insights into the eukaryotic RNase MRP ribonucleoprotein complex.

Zhou, Bin; Wang, Xiaozhu; Wan, Futang; Li, Shaobai; Zhang, Xiaoshuang; Zhang, Yuanyuan; Tan, Ming; Cao, Mi et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

RNase MRP is a conserved eukaryotic ribonucleoprotein essential for precursor-rRNA processing and ribosome assembly. Despite previous studies of yeast RNase MRP, the composition of RNase MRP and how it adapts to process flexible, single-stranded rRNA substrates in most eukaryotes remain enigmatic. Here, we perform an integrative structural, evolutionary, and functional dissection of human RNase MRP. Using structure-based bioinformatics and cryo-EM structural analyses, we identify NEPRO (RMP64) and C18orf21 (RMP24) as the bona fide subunits unique to RNase MRP, which are indispensable for precursor-rRNA cleavage, ribosome assembly, protein synthesis, and chondrogenesis. The structure of human RNase MRP reveals a unique 'double-anchor' substrate-binding mechanism that underlies evolutionary adaptations conferring broad substrate specificity. Our work on RNase MRP provides a unified evolutionary and mechanistic framework for this essential ancient ribozyme.