The colicin and lectin-like bacteriocins are a broad class of antimicrobial proteins produced by Gram-negative bacteria. They are generally narrow spectrum, killing or inhibiting the growth of closely related bacteria. Numerous Gram-negative bacteria that are important pathogens of both animals and plants produce and are susceptible to these bacteriocins. As such, these proteins represent an attractive alternative to traditional small molecule antibiotics for controlling bacterial infection.
Very little is known about bacteriocins produced by Gram-negative plant pathogens and so the aim of this work was to discover novel bacteriocins active against globally important plant pathogens from the genera Pectobacterium and Pseudomonas. The bacteriocins discovered in this study were then structurally and functionally characterised and assessed for their ability to impart disease resistance when expressed in a model transgenic system.
This study presents the discovery and characterisation of the bacteriocins syringacin M, syringacin L1 and pyocin L1 from the genus Pseudomonas, As well as the discovery and characterisation of the unusual ferredoxin containing pectocins from the genus Pectobacterium. Also presented is the discovery of a novel virulence related ferredoxin/iron-uptake system in Pectobacterium, which is parasitised by the pectocins for cell entry. Additionally, the transgenic expression of the bacteriocin putidacin L1 in both Arabidopsis thaliana and Nicotiana benthamiana was shown to provide these plants with resistance to infection by strains of the plant pathogen P. syringae
