Investigating substrate discrimination by the fission yeast La protein during stress

The La protein is an RNA-binding protein first identified as an autoantigen in Lupus patients. La’s best characterized function is to protect the 3’ end of pre-tRNAs from degradation by binding their characteristic UUU-3’OH tails. La also facilitates pre-tRNA folding through a poorly understood RNA chaperone mechanism. We hypothesized that the Schizosaccharomyces pombe La protein (Sla1p) discriminates among RNA substrates based on fold, selectively binding misfolded RNAs for chaperone intervention during cellular stresses predicted to disrupt RNA structure. High-throughput sequencing of Sla1p-associated RNAs did not reveal altered interaction between Sla1p and pre-tRNAs during stress, suggesting a lack of substrate discrimination by Sla1p. Northern blotting revealed novel perturbations to pre-tRNA processing in S. pombe during oxidative stress and nutrient starvation. Overall, this work has added to our understanding of La’s chaperone activity, and seeded future work toward uncovering further details of stress-dependent alterations to pre-tRNA processing in fission yeast.