Protein toxin complexes of Photorhabdus luminescens

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Photorhabdus luminescens is mutualistically associated with nematodes, which invade and kill insect larvae by means of the bacteria. Therefore, nematodes carrying bacteria are used as insecticides. Toxin complexes (Tc toxins) from P. luminescens, consisting of three components TcA, TcB and TcC, are essential for prevailing of bacteria and nematodes in the insect host. Recently, we have shown that two TcC components (TccC3 and TccC5) are ADP-ribosyltransferases. Whereas TccC3 ADP-ribosylates actin at threonine-148 to induce actin polymerization, TccC5 modifies Rho-GTPases at glutamine-63/61 to constitutively activate the GTPases. In the project the toxin complex is analyzed. The functional consequences and structural and biochemical requirements of the ADP-ribosylation will be studied. Furthermore, topic of the project is the analysis of the functions of TcA and TcB components of Tc toxin. It is proposed that the study elucidates the mode of actions and the interactions of the components of a new toxin family, which is found in several entomopathogenic bacteria but also in human pathogens.