Defining the import mechanism of pyocin AP41 and klebicin G (360G-Wellcome-203936_Z_17_A)

There is an urgent need to develop new antibiotics against multidrug resistant Gram-negative bacteria such as Pseudomonas aeruginosa and Klebsiella pneumoniae. These organisms are major causes of pneumonia and sepsis, with recent reports identifying hospital isolates of each resistant to all known antibiotics. The present research focuses on the mode of action of a family of antibiotic proteins known as nuclease bacteriocins that have not been developed as antimicrobials, but show promise in animal models of infection. Nuclease bacteriocins are species-specific toxins that are used by bacteria to compete with their neighbours. Although folded proteins these molecules are capable of penetrating the defences of Gram-negative bacteria to deliver an enzyme to the organism’s cytoplasm to degrade essential nucleic acids by an unknown mechanism. Two types of nuclease bacteriocin will be investigated, pyocin AP41 which targets Pseudomonas aeruginosa, and klebicin G which targets Klebsiella pneumoniae. Preliminary computational and experimental work on pyocin AP41 has identified potential candidate proteins involved in its import. This will be followed up with structure and function studies of AP41, a dissection of its import mechanism and new studies on klebicin G, a nuclease bacteriocin that has only recently been identified.