Full text loading...
Chapter 55 : Identification of Target Proteins of the Lss Secretion System of Legionella pneumophila Corby
This chapter describes a first putative type I secretion system (Lss) of Legionella pneumophila which is encoded by the lssXYZABD locus. In order to identify substrates of this Lss secretion system, the authors performed comparative two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) analysis of extracellular proteins of L. pneumophila Corby wild type, Corby lssB mutant, and complemented lssB mutant strain. In this study it was shown that the identified VirK protein of L. pneumophila is secreted in an LssB- but not a TatC-dependent manner. Referring to the results, it is implied that the Lss secretion system is also linked to the Lsp type II secretion system in L. pneumophila. It is speculated that VirK and p14 are secreted via a concerted action of the Lss and the Lsp system which includes cleavage of the signal sequences during secretion. In Agrobacterium and Rhizobium VirK is associated with the vir-regulon, and it was postulated that VirK should have a function in the interaction of the bacteria with the host cells. Therefore, the authors started to generate a virK mutant strain of L. pneumophila Corby and an antibody against VirK to further characterize the expression, secretion, and function of VirK of L. pneumophila.