InterPro: IPR002730 Ribonuclease P/MRP, subunit p29, eukaryotic/archaeal

This entry represents the p29 subunit (also known as Rpp29 or Pop4) of the related ribonucleoproteins ribonuclease (RNase) P and RNase MRP, which can be found in both eukaryotes and arachea [1]. The structure of the RNase P subunit, Rpp29, from Methanobacterium thermoautotrophicum has been determined. Mth Rpp29 is a member of the oligonucleotide/oligosaccharide binding fold family. It contains a structured beta-barrel core and unstructured N- and C-terminal extensions bearing several highly conserved amino acid residues that could be involved in RNA contacts in the protein-RNA complex [2]. Rpp29 (EC:3.1.26.5) catalyses the endonucleolytic cleavage of RNA, removing 5'-extranucleotides from tRNA precursor. It interacts with the Rpp25 and Pop5 subunits.

RNase P is a ubiquitous ribonucleoprotein enzyme primarily responsible for cleaving the 5' leader sequence during maturation of tRNAs in all three domains of life. In eubacteria, this enzyme is made up of two subunits: a large RNA (approximately 120 kDa) responsible for mediating catalysis, and a small protein cofactor (approximately 15 kDa) that modulates substrate recognition and is required for efficient in vivo catalysis. In contrast, multiple proteins are associated with eukaryotic and archaeal RNase P, and these proteins exhibit no recognizable homology to the conserved bacterial protein subunit. In reconstitution experiments with recombinantly expressed and purified protein subunits Mth Rpp29, a homologue of the Rpp29 protein subunit from eukaryotic RNase P, is an essential protein component of the archaeal holoenzyme [2]. In Saccharomyces cerevisiae (Baker's yeast), RNase P consists of 9 protein subunits (Pop1, Pop3-8, Rpr2 and Rpp1), while in humans there are 10 subunits (Rpp14, 20, 21, 25, 29, 30, 38, 40, hPop1, 5).

RNase MRP (mitochondrial RNA processing) is an rRNA processing enzyme that cleaves a specific site within precursor rRNA to generate the mature 5'-end of 5.8S rRNA [3]. RNase MRP also cleaves primers for mitochondrial DNA replication and CLB2 mRNA. In yeast, RNase MRP possesses one putatively catalytic RNA and at least 9 protein subunits and is highly related to RNase P (Pop1, Pop3-Pop8, Rpp1, Snm1 and Rmp1).