B53: Decoding Yeast Ribosomal Protein L7B's Autoregulatory Mechanism

Presenter(s)

Anirudh Kesanapally

Abstract or Description

Eukaryotes feature distinctive introns, or gene-encoded nucleotide sequences not directly involved in protein translation. Despite exclusion from the final mRNA transcript, introns crucially regulate genes, with many mechanisms still unknown. Post-transcriptional autoregulation, observed in yeast, serves as one such model for exploration and is commonplace within the yeast ribosome system. We aim to unveil a novel autoregulatory mechanism in a specific yeast gene, hypothesizing its applicability to more complex eukaryotes, and ultimately illuminating intron-dependent regulation. Building on the Stormo/White Lab's identification of autoregulated yeast ribosomal protein genes, our study focuses on genes with autoregulatory mechanisms that involve splicing inhibition. By selecting genes with conserved RNA intron structures across yeast species, we proceeded to monitor expression by attaching GFP reporter genes of these genes when overexpressing their corresponding protein. Remarkably, RPL7, specifically the analog RPL7B, a ribosomal protein gene, exhibited a ten-fold expression reduction upon RPL7 protein overexpression. From here, our exploration of RPL7's autoregulation took two paths. Deletions of the conserved intron structure by a lab scientist showed that various elements of RPL7’s intron structure prevented autoregulation, emphasizing the structure's significance. Concurrently, I conducted a protein-RNA binding experiment confirming the direct interaction of the conserved intron structure with RPL7 protein and thus identified critical intron regions of RPL7 that bind with RPL7’s protein product to achieve autoregulation. These results extrapolate RPL7's unique gene regulation methodology, underscoring the importance of unique intron structural elements in studying eukaryotic gene expression.