Conservation of the trblGene Across Drosophila Species: How Does Structure Support Function?

Abstract

In collaboration with the Genomics Education Partnership (thegep.org), we seek to understand how genes functioning in the insulin signaling pathway evolve. In Drosophila melanogaster, the gene tribbles(trbl) codes for a protein that binds to Akt (also known as Protein Kinase B) and blocks Akt‐mediated insulin signaling. Trbl misexpression also affects the Akt target, Foxo (Forkhead box transcription factor). In humans, expression of trblorthologs is associated with degradation of substrates through E3 ligase‐dependent ubiquitination. Misexpression of TRIB2, one of the three Tribbles pseudokinases in humans, has been found to be associated with certain cancers. Our initial research consisted of annotating orthologs of trbland more recently foxoacross the genus Drosophilato look at conservation within the fly species. In order to identify orthologs, we considered synteny of the genomic neighborhood and determined conservation with the D. melanogasterprotein using BLAST. We then determined the location of the coding exons using data available in the UCSC Genome Browser, creating a gene model to evaluate how well our proposed gene matches the D. melanogaster ortholog. In addition to this process, we also used sequence alignments as well as structural databases to gather information about conservation of the Trbl orthologs among seven species. Trbl orthologs across Drosophilashow 60‐70% amino acid similarity. The highest degree of conservation is within the pseudokinase domain, which takes up the majority of the structure of the gene, for both Drosophilaand humans. Multiple sequence alignments reveal that the N‐ and C‐termini show less conservation and are shorter in human orthologs as compared to Drosophila proteins. This is significant as those regions in human TRIBs have documented functions in protein degradation. Continuing this work, we hope to gain a better understanding of how the structure of Trbl/TRIB proteins supports their function, including with other players in the insulin signaling pathway.