Characterization of TRZ1, a yeast homolog of the human candidate prostate cancer susceptibility gene ELAC2 encoding tRNase Z.

In humans, mutation of ELAC2 is associated with an increased risk of prostate cancer. ELAC2 has been shown to have tRNase Z activity and is associated with the gamma-tubulin complex. In this work, we show that the yeast homolog of ELAC2, encoded by TRZ1 (tRNase Z 1), is involved genetically in RNA processing. The temperature sensitivity of a trz1 mutant can be rescued by multiple copies of REX2, which encodes a protein with RNA 3' processing activity, suggesting a role of Trz1p in RNA processing in vivo. Trz1p has two putative nucleotide triphosphate-binding motifs (P-loop) and a conserved histidine motif. The histidine motif and the putative nucleotide binding motif at the C-domain are important for Trz1p function because mutant proteins bearing changes to the critical residues in these motifs are unable to rescue deletion of TRZ1. The growth defect exhibited by trz1 yeast is not complemented by the heterologous ELAC2, suggesting that Trz1p may have additional functions in yeast. Our results provide genetic evidence that prostate cancer susceptibility gene ELAC2 may be involved in RNA processing, especially rRNA processing and mitochondrial function.