James W. Brown

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

Armbruster DW, Hass ES, Brown JW, Daniels CJ.
International C. elegans Meeting, June 25-29, 1995, Los Angeles, CA

Ribonuclease P (RNase P) is a ribonucleoprotein enzyme in which the RNA is the catalytically active subunit. Current models for the structure of the bacterial RNase P RNA are derived from phylogenetic sequence comparisons, chemical and enzymatic structure probings, and functional analysis of mutant RNAs. We have set out to refine the Archaeal RNase P RNA structure by undertaking a phylogenetic study of RNase Ps from the euryarchaeota branch of the Archaea. We have sequenced the RNase P genes from four halophiles (Halococcus morrhuae, Halobacterium cutirubrum, Halobacterium trapanicum, Natronobaterium gregoryi, and one methanogen (Methanosarcina barkeri). These RNase P RNAs are characteristically bacterial in sequence and structure, yet lack catalytical activity in the absence of protein. The Archaeal consensus differs from the bacterial consensus at conserved nucleotides: 19, 68,124, 330, and 358 (numbering base on M1 RNA). Two minor structural features are also absent: a conserved bulged loop and adjacent short helix (M1 nucleotides 122-126 and 235-235). We are presently investigating whether the lack of RNA-alone activity can be attributed to these structural and sequence differences.

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