Separate RNA-binding Surfaces on the Multifunctional La Protein Mediate Distinguishable Activities in tRNA Maturation

Nat Struct Mol Biol. 2006 Jul;13(7):611-8. doi: 10.1038/nsmb1110. Epub 2006 Jun 25.

Abstract

By sequence-specific binding to 3' UUU-OH, the La protein shields precursor (pre)-RNAs from 3' end digestion and is required to protect defective pre-transfer RNAs from decay. Although La is comprised of a La motif and an RNA-recognition motif (RRM), a recent structure indicates that the RRM beta-sheet surface is not involved in UUU-OH recognition, raising questions as to its function. Progressively defective suppressor tRNAs in Schizosaccharomyces pombe reveal differential sensitivities to La and Rrp6p, a 3' exonuclease component of pre-tRNA decay. 3' end protection is compromised by mutations to the La motif but not the RRM surface. The most defective pre-tRNAs require a second activity of La, in addition to 3' protection, that requires an intact RRM surface. The two activities of La in tRNA maturation map to its two conserved RNA-binding surfaces and suggest a modular model that has implications for its other ligands.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Conserved Sequence
  • Humans
  • Molecular Sequence Data
  • Mutagenesis
  • RNA Processing, Post-Transcriptional / genetics
  • RNA, Fungal / genetics
  • RNA, Transfer / genetics*
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Recombinant Proteins / metabolism
  • Schizosaccharomyces / genetics*
  • Schizosaccharomyces pombe Proteins / genetics
  • Schizosaccharomyces pombe Proteins / metabolism*
  • Sequence Alignment
  • Suppression, Genetic

Substances

  • RNA, Fungal
  • RNA-Binding Proteins
  • Recombinant Proteins
  • Schizosaccharomyces pombe Proteins
  • sla1 protein, S pombe
  • RNA, Transfer