Maturation of Lipoproteins by Type II Signal Peptidase Is Required for Phagosomal Escape of Listeria monocytogenes

An Important Step inListeriaLipoprotein Research

“…The in vitro infection assays described by Baumgärtner et al showed that the lgt mutant had a slight defect for proliferation in nonphagocytic cells, which correlated with subtle differences in the growth rate observed in minimal growth medium (2). These data, which parallel those obtained with macrophages and the lsp mutant (13), suggest that L. monocytogenes might cope with some nutritional stress when it resides in the cytosol of the infected cell. Up-regulation of certain nutrient transporters, such as Hpt, a glucose-6-phosphate translocator, has been shown to mediate rapid proliferation of L. monocytogenes inside eukaryotic cells (5).…”

“…Similar to Lgt, the lipoprotein-specific signal peptidase Lsp has been shown to be dispensable for growth in several grampositive bacteria, including L. monocytogenes (6,13,21,23). These findings contrast with those obtained for gram-negative bacteria, in which both Lgt and Lsp are essential enzymes.…”

“…OppA promotes survival in macrophages and in mouse organs, whereas it has been proposed that LpeA mediates bacterial entry into eukaryotic cells (3,14). Indirect evidence for an important role of lipoproteins in L. monocytogenes vir- ulence was also obtained with an lsp mutant, which displayed defects in phagosomal escape upon entry into macrophages (13). This observation suggests that the intracellular infection cycle of L. monocytogenes, which includes an early intraphagosomal stage followed by lysis of the phagosomal membrane and intracytosol proliferation, depends on correct insertion into the membrane of an unidentified set of lipoproteins.…”

Lipoprotein biogenesis in Gram-positive bacteria: knowing when to hold ‘em, knowing when to fold ‘em

“…L. monocytogenes, Staphylococcus epidermidis, Nocardia farcinica) a second Lsp paralogue seems to be present. Some separate functionality is suggested for these Lsp paralogues: in the case of N. farcinica, the Lsp paralogue is plasmid encoded, whereas in L. monocytogenes inactivation of LspA (lmo1844) did not seem to be compensated for by the presence of the lmo1101 paralogue [32].…”

The arsenal of virulence factors deployed byListeria monocytogenesto promote its cell infection cycle

“…141 Lsp is a signal peptidase responsible for the maturation of L. monocytogenes lipoproteins. 142 Mutation of the lsp gene results in a decrease in the ability to escape from phagosomes during infection of eukaryotic cells, which leads to low levels of virulence. In addition, expression of lsp is highly upregulated by bacteria still enclosed in infected macrophage phagosomes, suggesting a role for Lsp and lipoprotein maturation in the phagosomal escape of L. monocytogenes.…”