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RNase P: increased versatility through protein complexity?

Michael C. Marvin and David R. Engelke

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Ribonuclease P (RNase P) is an essential enzyme that catalyzes the 5’ endonucleolytic cleavage of precursor transfer RNAs (pre-tRNAs).  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, and several lines of evidence suggest 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.  The involvement of RNase P in multiple RNA processing pathways is discussed.

Authors

Michael C. Marvin

Department of Biological Chemistry; University of Michigan School of Medicine; Ann Arbor, Michigan USA

David R. Engelke Corresponding author: engelke@umich.edu

Department of Biological Chemistry; University of Michigan School of Medicine; Ann Arbor, Michigan USA

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