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Evidence for an RNA-based catalytic mechanism in eukaryotic nuclear ribonuclease P.
Thoms, Brian C. Chamberlain, Joel Engelke, David R. Gegenheimer, Peter Albert
Thoms, Brian C.
Chamberlain, Joel
Engelke, David R.
Gegenheimer, Peter Albert
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Abstract
Ribonuclease P is the enzyme responsible for removing the 5'-leader segment of precursor transfer RNAs in all organisms. All eukaryotic nuclear RNase Ps are ribonucleoproteins in which multiple protein components and a single RNA species are required for activity in vitro as well as in vivo. It is not known, however, which subunits participate directly in phosphodiester-bond hydrolysis. The RNA subunit of nuclear RNase P is evolutionarily related to its catalytically active bacterial counterpart, prompting speculation that in eukaryotes the RNA may be the catalytic component. In the bacterial RNase P reaction, Mg(II) is required to coordinate the nonbridging phosphodiester oxygen(s) of the scissile bond. As a consequence, bacterial RNase P cannot cleave pre-tRNA in which the pro-Rp nonbridging oxygen of the scissile bond is replaced by sulfur. In contrast, the RNase P reaction in plant chloroplasts is catalyzed by a protein enzyme whose mechanism does not involve Mg(II) coordinated by the pro-Rp oxygen. To determine whether the mechanism of nuclear RNase P resembles more closely an RNA- or a protein-catalyzed reaction, we analyzed the ability of Saccharomyces cerevisiae nuclear RNase P to cleave pre-tRNA containing a sulfur substitution of the pro-Rp oxygen at the cleavage site. Sulfur substitution at this position prohibits correct cleavage of pre-tRNA. Cleavage by eukaryotic RNase P thus depends on the presence of a thio-sensitive ligand to the pro-Rp oxygen of the scissile bond, and is consistent with a common, RNA-based mechanism for the bacterial and eukaryal enzymes.
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This is the published version. Copyright 2000 by the RNA Society.
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2000
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RNA Society
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Thomas, Brian C., Joel Chamberlain, David R. Engelke, and Peter Gegenheimer. "Evidence for an RNA-based Catalytic Mechanism in Eukaryotic Nuclear Ribonuclease P." Rna 6.4 (2000): 554-62. Web.