Analysis of putative RNase P RNA from orthopoxviruses

A putative RNase P RNA gene in camelpox virus, one of the orthopoxviruses, was cloned and transcribed in vitro. No RNase P activity could be detected in vitro from camelpox virus RNase P RNA alone, or by addition of the Escherichia coli RNase P protein subunit to reaction mixtures. Camelpox virus RNase P RNA reconstituted in vitro with camel or HeLa cell extracts, which were pre-treated with micrococcal nuclease to degrade the endogenous RNase P RNA, showed no RNase P activity. Vaccinia virus, another orthopoxvirus, showed no RNase P activity in vaccinia-infected HeLa cells, even though transcription of the vaccinia RNase P RNA could be identified in the cells by both Northern blot and RNase protection assay. Camelpox virus RNase P RNA inhibited an endogenous HeLa RNase P activity by 20% in our assays. The 5S RNA showed no significant inhibition in this assay.