Reaction in vitro of some mutants of RNase P with wild-type and temperature-sensitive substrates

Leif A. Kirsebom, Sidney Altman

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28 Scopus citations


The reaction of wild-type and two mutant derivatives of RNase P have been examined with wild-type and mutant substrates. We show that a mutant derivative of tRNA TyrSu3, tRNA TyrSu3A15, in which the G15 · C48(57) base-pair essential for folding of the tRNA moiety is altered, is a temperature-sensitive suppressor in vivo. The precursor to tRNA TyrSu3A15 is cleaved in a temperature-sensitive manner in vitro by RNase P and with a higher Km compared to the precursor to tRNA TyrSu3. The precursor to tRNA TyrSu3A2, another temperature-sensitive suppressor in vivo in which the G2 · C71(80) base-pair in the acceptor stem is changed to A2 · C71(80), behaves like the precursor to tRNA TyrSu3 in vitro; that is, it is not cleaved in a temperature-sensitive manner. Therefore, there are at least two ways in which a suppressor tRNA can acquire a temperature-sensitive phenotype in vivo. One of the mutant derivatives of RNase P we have tested, rnpA49, which affects the protein cofactor of the enzyme, has a decreased kcat compared to wild-type, which can explain its phenotype in vivo.

Original languageEnglish (US)
Pages (from-to)837-840
Number of pages4
JournalJournal of molecular biology
Issue number4
StatePublished - Jun 20 1989
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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