Human mitochondrial TyrRS disobeys the tyrosine identity rules

RNA. 2005 May;11(5):558-62. doi: 10.1261/rna.7246805.

Abstract

Human tyrosyl-tRNA synthetase from mitochondria (mt-TyrRS) presents dual sequence features characteristic of eubacterial and archaeal TyrRSs, especially in the region containing amino acids recognizing the N1-N72 tyrosine identity pair. This would imply that human mt-TyrRS has lost the capacity to discriminate between the G1-C72 pair typical of eubacterial and mitochondrial tRNATyr and the reverse pair C1-G72 present in archaeal and eukaryal tRNATyr. This expectation was verified by a functional analysis of wild-type or mutated tRNATyr molecules, showing that mt-TyrRS aminoacylates with similar catalytic efficiency its cognate tRNATyr with G1-C72 and its mutated version with C1-G72. This provides the first example of a TyrRS lacking specificity toward N1-N72 and thus of a TyrRS disobeying the identity rules. Sequence comparisons of mt-TyrRSs across phylogeny suggest that the functional behavior of the human mt-TyrRS is conserved among all vertebrate mt-TyrRSs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Catalytic Domain
  • Humans
  • Mitochondria / enzymology*
  • Molecular Sequence Data
  • RNA, Transfer, Tyr / genetics
  • RNA, Transfer, Tyr / metabolism*
  • Substrate Specificity
  • Tyrosine / genetics
  • Tyrosine / metabolism*
  • Tyrosine-tRNA Ligase / chemistry
  • Tyrosine-tRNA Ligase / metabolism*

Substances

  • RNA, Transfer, Tyr
  • Tyrosine
  • Tyrosine-tRNA Ligase