Liu Yuan, He Shiyang, Pyo Kawon, Zheng Shanshan, Chen Meijuan, Braschi Bryony, Cheloufi Sihem, Slavov Nikolai, Marzluff William F, Murn Jernej
Department of Biochemistry, University of California, Riverside, CA 92521, United States.
Center for RNA Biology and Medicine, University of California, Riverside, CA 92521, United States.
Nucleic Acids Res. 2025 Aug 27;53(16). doi: 10.1093/nar/gkaf829.
Ribonuclease (RNase) MRP is a conserved RNA-based enzyme best known for its essential role in the maturation of ribosomal RNA (rRNA) in eukaryotes. However, the composition and RNA substrate specificity of this multisubunit ribonucleoprotein complex in higher eukaryotes remain a mystery. Here, we identify NEPRO and C18ORF21 (which we renamed RMP64 and RMP24, respectively) as constitutive subunits of metazoan RNase MRP. These proteins are unique to RNase MRP and absent from the closely related RNase P, which processes transfer RNA (tRNA) precursors and tRNA-like substrates. We find that RMP64 and RMP24 are integral subunits of RNase MRP, stabilize its catalytic RNA, and are required for rRNA maturation and cell proliferation. Leveraging these discoveries, we identify a broad suite of in vivo RNA-binding targets of each enzyme, including potential cleavage sites at nucleotide resolution. Our findings identify the first metazoan RNase MRP-specific protein subunits and define the RNA-targeting repertoire of this essential enzyme in mammalian cells.
核糖核酸酶（RNase）MRP是一种保守的基于RNA的酶，因其在真核生物核糖体RNA（rRNA）成熟过程中的关键作用而闻名。然而，这种多亚基核糖核蛋白复合物在高等真核生物中的组成和RNA底物特异性仍是个谜。在此，我们鉴定出NEPRO和C18ORF21（我们分别将其重新命名为RMP64和RMP24）作为后生动物RNase MRP的组成亚基。这些蛋白质是RNase MRP所特有的，在密切相关的处理转运RNA（tRNA）前体和tRNA样底物的核糖核酸酶P中不存在。我们发现RMP64和RMP24是RNase MRP的组成亚基，能稳定其催化RNA，并且是rRNA成熟和细胞增殖所必需的。利用这些发现，我们确定了每种酶在体内的一系列广泛的RNA结合靶点，包括核苷酸分辨率下的潜在切割位点。我们的研究结果鉴定出了首个后生动物RNase MRP特异性蛋白质亚基，并定义了这种关键酶在哺乳动物细胞中的RNA靶向范围。
