The LARP1 homolog Slr1p controls the stability and expression of proto-5'TOP mRNAs in fission yeast [RNA-seq]
Messenger RNAs (mRNAs) in higher eukaryotes that encode highly expressed proteins important for the assembly of the translational apparatus (e.g. ribosomal proteins) often harbour a pyrimidine-rich motif at the extreme 5' end known as a 5' terminal oligopyrimidine (5'TOP) sequence. Members of the La-related protein 1 (LARP1) family control 5'TOP expression through a conserved DM15 motif, but the mechanism is not well understood. 5'TOP motifs have not been described in many lower organisms, but fission yeast (and many other single-celled eukaryotes) harbour a LARP1 homolog that also lacks a DM15 motif. In this work, we show that the fission yeast LARP1 homolog, Slr1p, controls the translation and stability of mRNAs encoding proteins analogous to 5'TOP mRNAs in higher eukaryotes, which we thus refer to as proto-5'TOPs. Our data suggest that the LARP1 DM15 motif and the mRNA 5'TOP motif may be features that were scaffolded over a more fundamental mechanism of LARP1 family member-associated control of gene expression that is still utilized in lower systems. Overall design: To study RNA abundance in presence and absence of Slr1p in S. pombe, translational profiling was performed with wildtype yAS99 cells and slr1- cells. This was followed by RNA-Seq of total RNA and polysome-associating RNAs. Sequencing was performed for two biological replicates.