Evolution of Nuclease Bacteriocins

Presenter

Sofia Blomqvist

Campus

UMass Amherst

Sponsor

Margaret Riley, Department of Biology, UMass Amherst

Schedule

Session 4, 2:30 PM - 3:15 PM [Schedule by Time][Poster Grid for Time/Location]

Location

Poster Board A76, Campus Center Auditorium, Row 4 (A61-A80) [Poster Location Map]

Abstract

Bacteriocins are antimicrobial proteins produced by bacteria to kill closely-related species as a means to decrease competition for resources. Colicins, which are bacteriocins produced by and targeting Escherichia coli, have historically been used as a model for bacteriocin evolution and ecology, and are the major members of a group of gram negative bacteriocins called colicin-like bacteriocins (CLBs). This study focuses on nuclease CLBs, which kill target cells through degradation of DNA, rRNA, or tRNA. We created phylogenetic trees from protein alignments of 30 nuclease CLBs spanning 5 medically-relevant species in order to infer evolutionary relationships and selective pressures. We found that nucleases exhibit much more diversity in their killing domains than in the rest of the protein, which tends to be more highly conserved in a species-specific manner. Phylogenetic trees of the killing domain, on the other hand, group the nucleases broadly by target molecule, with some exceptions. We hypothesize that this is a result of proteolytic processing during translocation into the cytoplasm, cleaving the killing domain from the rest of the protein and allowing it to act as a separate unit of evolution. Despite the increased diversity of the killing domain, certain residues are highly conserved within killing types, corresponding to functionally-important residues. Understanding of the evolution of these antimicrobials is important to their potential use as novel therapeutics and the effort of combating antimicrobial resistance.

Keywords

Phylogeny, Antimicrobials, Protein evolution

Research Area

Evolution

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