Modified bacteriocins and methods for their use
Modified forms of naturally occurring bacteriocins, such as the R-type pyocins of Pseudomonas aeruginosa , are disclosed as are methods for producing them in GRAS organisms. The bacteriocins are modified at the ends of their tail fibers in a region responsible for binding specificity and affinity to their cognate binding partners, or receptors, such as those on the surface of bacteria. Methods for the use of the modified bacteriocins, such as to bind receptors, including virulence or fitness factors, on the surfaces of bacteria, are also described.
1. An isolated bacterium comprising nucleic acid encoding proteins of an R-type high molecular weight (hmw) bacteriocin from another microorganism, wherein the bacterium expresses the proteins comprising the R-type hmw bacteriocin having bactericidal activity.
2. The bacterium of claim 1 which is classified as a GRAS (generally recognized as safe) bacterium.
3. The bacterium of claim 1 which is E. coli or Pseudomonas fluorescens.
4. The bacterium of claim 1 in which the expression of the bacteriocin proteins is under the control of a promoter heterologous to the bacteriocin.
5. The bacterium of claim 4 whereby an exogenous molecule acts as an inducer or co-repressor of the promoter to express or not express the R-type hmw bacteriocin proteins.
6. The bacterium of claim 1 wherein the nucleic acid encoding the R-type hmw bacteriocin proteins has an inactivated holin gene.
7. The bacterium of claim 6 , wherein the holin gene has been inactivated by deletion.