3′-processing of yeast tRNA^Trp precedes 5′-processing

Abstract

Previous analyses of eukaryotic pre-tRNAs processing have reported that 5′-cleavage by RNase P precedes 3′-maturation. Here we report that in contrast to all other yeast tRNAs analyzed to date, tRNA^Trp undergoes 3′-maturation prior to 5′-cleavage. Despite its unusual processing pathway, pre-tRNA^Trp resembles other pre-tRNAs, showing dependence on the essential Lsm proteins for normal processing and efficient association with the yeast La homolog, Lhp1p. tRNA^Trp is also unusual in not requiring Lhp1p for 3′ processing and stability. However, other Lhp1p-independent tRNAs, tRNA₂^Lys and tRNA₁^Ile, follow the normal pathway of 5′-processing prior to 3-processing.

Keywords

• tRNA processing
• La protein
• Lsm proteins
• Saccharomyces cerevisiae