Endonuclease RNase P responsible for the 5' maturation of tRNA precursors. Preferentially cleaves at the unusual cleavage site, but also able to cleave at the classical cleavage site. Also involved in the maturation of mRNAs in mitochondria. Endonucleolytic cleavage of RNA, removing 5'-extranucleotides from tRNA precursor. Binds 2 Mg(2+) or Mg(2+) ions per subunit. Embryo lethality when homozygous. Belongs to the PPR family. P subfamily.