RNase P: increased versatility through protein complexity?
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.
Marvin
Michael C
MC
Department of Biological Chemistry, University of Michigan School of Medicine, Ann Arbor, Michigan 48109-0606, USA.
Engelke
David R
DR
D000818:Animals; D001665:Binding Sites; D017124:Conserved Sequence; D006801:Humans; D007438:Introns; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry*; D012329:RNA, Bacterial / Q000378:metabolism; D016337:RNA, Catalytic / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D020537:RNA, Small Nucleolar / Q000737:chemistry*; D012343:RNA, Transfer / Q000737:chemistry; D022661:RNA, Untranslated / Q000737:chemistry*; D043262:Ribonuclease P / Q000737:chemistry* / Q000378:metabolism
D012329:RNA, Bacterial; D016337:RNA, Catalytic; D012333:RNA, Messenger; D020537:RNA, Small Nucleolar; D022661:RNA, Untranslated; D012313:RNA; D012343:RNA, Transfer; D043262:Ribonuclease P