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Chapter 63 : The Hsp60 Chaperonin of Legionella pneumophila: an Intriguing Player in Infection of Host Cells
This chapter reports that through genetic and functional studies in yeast and mammalian cells, the authors have demonstrates that Legionella pneumophila Hsp60 alters signaling cascades in eukaryotic cells, modifies the actin cytoskeleton of mammalian cells, and alters the trafficking of mitochondria in mammalian cells, making Hsp60 a potential effector in L. pneumophila’s intracellular establishment. The authors determined that dotA and dotB mutant derivatives of Lp02 had virtually no protease-accessible HtpB; i.e., these mutants displayed no surface-exposed HtpB. In addition, immunogold electron microscopy, performed with an HtpB-specific rabbit antiserum and a secondary gold-conjugated antibody against rabbit immunoglobulin, showed that the Lp02 dot mutants, particularly the dotB mutant, had an increased amount of periplasmic gold particles. This interesting result suggested that a nonfunctional Dot/Icm system results in the accumulation of HtpB in the periplasm. Recombinant HtpB caused Chinese hamster ovary (CHO) cells to lose their stress fibers. The abilities of HtpB to specifically alter eukaryotic signaling pathways, cytoskeletal organization, and organellar traffic are indeed functional characteristics that fit well into HtpB’s potential role as an L. pneumophila virulence effector.