James W. Brown

Associate Professor & Undergraduate Coordinator
Department of Microbiology, NC State University

2nd Annual State of North Carolina Undergraduate Research Symposium, November 18, 2006, Raleigh, NC

RNase P in Pyrobaculum?
D. MCLAURIN, A. LOTSTEIN, and J.W. BROWN. Department of Microbiology, NC State University, Raleigh, NC

When the genome sequence of the hyperthermophilic archaeon Pyrobaculum aerophilum was released in 2002, genes encoding neither the catalytically-active RNA subunit of the enzyme, nor any of the four highly-conserved protein subunits of the enzyme could be identified. Although essential for 5´ processing in the biosynthetic pathway of transfer RNAs, the apparent lack of all of the subunits of this enzyme was rationalized by the observation that consensus promoters could be identified immediately upstream of most tRNA genes; it was thought that tRNAs must be transcribed without 5´ leaders, and thus without the need for RNase P processing. However, in collaboration with Todd Lowe's group at UC Santa Cruz, we have recently identified a conserved putative RNase P RNA gene in an "intergenic spacer" in all 4 currently available Pyrobaculum species genome sequences. This RNA contains all of the most highly conserved sequence and structural elements known to be directly involved in substrate binding and catalysis, but lacks the otherwise highly conserved second domain involved in modulating substrate specificity and perhaps also containing the binding sites for the protein subunits. We are currently testing the functional competence of this RNA, and cell extracts, using a series of potential substrates including tRNA precursors with very short leaders.

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