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Identification of Translocated Substrates of the Legionella pneumophila Dot/Icm System without the use of Eukaryotic Host Cells, Page 1 of 2
< Previous page Next page > /docserver/preview/fulltext/10.1128/9781555815660/9781555813901_Chap45-1.gif /docserver/preview/fulltext/10.1128/9781555815660/9781555813901_Chap45-2.gifAbstract:
This chapter describes alternate approaches that take advantage of special properties of Legionella pneumophila strains that allowed the formulation of simple screens using toothpicks and petri dishes containing bacteriological medium. Developing readouts in the microorganism that allow screens on solid medium has allowed a number of translocated substrates to be identified. Interestingly, it was found that dotL mutants producing low levels of DotA were able to grow on agar plates. This important finding allowed considerable manipulation of phenotypes, because the behavior of mutants that would otherwise be inviable could now be evaluated during intracellular growth. The great majority of mutations, in fact, appeared to directly affect the assembly of the Dot/Icm system or disrupt function of DotL, and many of the impaired proteins are involved in either membrane biogenesis or membrane protein folding. In several T4SSs,Mob protein can be transferred into recipient cells in the absence of DNA mobilization, indicating that protein translocation into bacteria can occur in the same fashion that is observed when the pathogen contacts a mammalian cell. Furthermore, elimination of multiple paralogs of a single gene family does not solve the redundancy issue, suggesting that a similar amino acid sequence does not necessarily mean the proteins have similar functions. Development of functional and biochemical assays for these proteins will be necessary to sort out their roles in intracellular growth.