Characterisation of the Rex1 ribonuclease in yeast and human cells

Expression of the genetic information within all cells requires ribonuclease
enzymes, which act to process initial products of transcription to functional RNA
molecules, facilitate the degradation of functional RNAs at the end of their
lifetime and mediate quality control measures to ensure the accuracy of gene
expression. The Rex1 enzyme functions in multiple such pathways, including the
maturation of ribosomal RNA and transfer RNAs that are required for protein
synthesis. However, how the protein distinguishes its substrates from other
cellular RNAs, or is able to interact with its RNA substrates, is not known. From
data available in our lab, we postulate that regions outwith its catalytic domain
are required to mediate interactions with its substrates and other protein factors,
drive its nuclear import, or are responsible for stable expression of the catalytic
domain. Furthermore, the functionally homologous protein in somatic human
cells has not yet been identified. The project aims to map regions within the
yeast protein that are responsible for its molecular functions, to identify and
functionally characterise Rex1-interaction proteins, and to identify the protein(s)
within human cells that mediates the equivalent steps in rRNA and tRNA
processing.