Poster abstracts
Poster number 22 submitted by Yizhu Lin
Codon usage and position alter the functions of upstream open reading frames
Yizhu Lin (Department of Biological Sciences, Carnegie Mellon University), Gemma May (Department of Biological Sciences, Carnegie Mellon University), Pieter Spealman (Department of Biological Sciences, Carnegie Mellon University), Lauren Nazzaro (Department of Biological Sciences, Carnegie Mellon University), Hunter Kready (Department of Biological Sciences, Carnegie Mellon University), Joel McManus (Department of Biological Sciences, Carnegie Mellon University)
Abstract:
Translational regulation plays an important role in eukaryotic gene expression. Upstream Open Reading Frames (uORFs) are important regulatory elements located in 5’ mRNA transcript leaders. Translation of uORFs usually inhibit the translation of downstream main open reading frame (mORF), but some enhance expression. While a minority of uORFs encode conserved functional peptides, the coding regions of most uORFs are not conserved. Thus, the impact of uORF coding sequences on their regulatory functions remains largely unknown. We investigated the impact of uORF coding regions on their functions by using a massively parallel reporter assay (FACS-uORF) to determine the regulatory functions of thousands of variants of a uORF from the yeast YAP1 gene. Varying uORF codons resulted in a wide range of functions, including both repressor and enhancer uORFs. The presence of rare codons resulted in the most inhibitory uORF variants. Inhibitory functions of such uORFs were abrogated by overexpression of complementary tRNA. Finally, regression analysis of our results indicated that both codon identity and position impact uORF functions. Our results support a model in which uORF coding sequences impact their regulatory functions by altering the speed of uORF translation.
Keywords: uORF, translation, codon usage