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RNA Biol. 2009 Jan-Mar;6(1):40-2. Epub 2009 Jan 3.

RNase P: increased versatility through protein complexity?

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Department of Biological Chemistry, University of Michigan School of Medicine, Ann Arbor, Michigan 48109-0606, USA.


Ribonuclease P (RNase P) is an essential enzyme that catalyzes the 5' endonucleolytic cleavage of precursor transfer RNAs (pretRNAs). It is found in all phylogenetic domains: bacteria, archaea and eukaryotes. The bacterial enzyme consists of a single, catalytic RNA subunit and one small protein, while the archaeal and eukaryotic enzymes have 4-10 proteins in addition to a similar RNA subunit. The bacterial RNA acts as a ribozyme at high salt in vitro; however the added protein optimizes kinetics and makes specific contacts with the pre-tRNA substrate. The bacterial protein subunit also appears to be required for the processing of non-tRNA substrates by broadening recognition tolerance. In addition, the immense increase in protein content in the eukaryotic enzymes suggests substantially enlarged capacity for recognition of additional substrates. Recently intron-encoded box C/D snoRNAs were shown to be likely substrates for RNase P, with several lines of evidence suggesting that the nuclear holoenzyme binds tightly to, and can cleave single-stranded RNA in a sequence dependent fashion. The possible involvement of RNase P in additional RNA processing or turnover pathways would be consistent with previous findings that RNase MRP, a variant of RNase P that has evolved to participate in ribosomal RNA processing, is also involved in turnover of specific messenger RNAs. Here, involvement of RNase P in multiple RNA processing pathways is discussed.

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