Molecular Investigations into the targeting of tailocins from the Kiwifruit pathogen Pseudomonas syringae pv. actinidiae (PSA)

Abstract

Kiwifruit are a significant agricultural crop for New Zealand, representing a multi-billion dollar industry. However, in 2008 crops were decimated worldwide as a result of the plant pathogen Pseudomonas syringae pv. actinidiae (PSA). While manageable, it still poses problems for the industry, and strategies that target PSA without having adverse effects on soil microbes are needed. Many PSA strains express phage resembling structures termed tailocins that selectively kill competing and closely related bacteria. Moreover, the tail-fibre domains of tailocins are suggested to determine selectivity by binding to specific Lipopolysaccharide (LPS) variants. Yet the molecular workings for this remain unclear. Thus this project aims to uncover the targeting mechanisms for tailocins in the P. syringae species. Tail-fibres have been expressed using an E. coli T7 system and subsequently purified using affinity and size-exclusion chromatography. Tailocins have been expressed from their native strains and their targeting abilities quantified. Further, LPS is assessed as the receptor for P. syringae tailocins. Overall this research will provide information currently absent from the literature surrounding how tailocins target, with the hope to uncover PSA sensitive strains, and is the first step towards exploiting tailocin activity for PSA biocontrol.