Tuesday, August 28, 2018 - 13:00 to 14:00
MSI Small Lecture Theatre
Professor Geoff Barton FRSE FRSB
Dr Richard Edwards
University of New South Wales, Sydney
One of the most important, interesting and challenging questions in biology is how new traits evolve at the molecular level. My lab employs sequence analysis techniques to interrogate protein and DNA sequences for the signals left behind by evolution. In this talk, I will explore two main themes in the evolution of novelty that we study in my lab.
Many protein-protein interactions are mediated by Short Linear Motifs (SLiMs): short stretches of proteins (5-15 amino acids long), of which only a few positions are critical to function. These motifs are vital for biological processes of fundamental importance, acting as ligands for molecular signalling, post-translational modifications and subcellular targeting. SLiMs have extremely compact protein interaction interfaces, generally encoded by less than 4 major affinity-/specificity-determining residues. Their small size enables high functional density and evolutionary plasticity, making them frequent products of convergent "ex nihilo" evolution. It also makes them challenging to identify, both experimentally and computationally. In the first half of the seminar, I will focus on developments in computational methods for the prediction of SLiMs from sequence and interaction data. I will give an overview of my contributions to this exciting and expanding field, with a particular emphasis on some of the tools that I have developed for SLiM prediction. These developments, combined with dramatic improvements in the quantity and quality of the underlying data, mean that we can now predict SLiMs with good confidence measures and are looking increasingly to applications. Of particular interest is the study of rapidly evolving pathogens that exploit host SLiMs and use them to hijack cellular processes.
In the second half of the seminar, I will explore how different modern sequencing technologies can be combined to investigate the genes and mutations involved in the evolution of a novel metabolic trait. The conversion of xylose to ethanol is vital for second generation biofuel production. Our collaborator, Microbiogen Pty Ltd., has successfully evolved a Saccharomyces cerevisiae (Baker’s yeast) strain that grows efficiently on xylose as a sole carbon source. This is a novel metabolic activity, absent from its parents and wild yeast strains. We are combining comparative genomics, evolutionary genetics, RNA-Seq transcriptomics, and competition assays to understand how the novel metabolism evolved. Through deep Illumina resequencing of evolving populations, and assembling reliable complete genomes of the founding ancestors, the ultimate goal is to trace how mutations have interacted with existing genetic variation during adaptive evolution.