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Mutants of Salmonella typhimurium lacking DNA adenine methylase are attenuated for virulence in BALB/c mice. LD(50) values of a DNA adenine methylation (Dam)(-) mutant are at least 10(3)- to 10(4)-fold higher than those of the parental strain when administrated by oral or intraperitoneal routes. Dam(-) mutants are unable to proliferate in target organs but(More)
During infection of their hosts, Gram-positive bacteria express surface proteins that serve multiple biological functions. Surface proteins harbouring a C-terminal sorting signal with an LPXTG motif are covalently linked to the cell wall peptidoglycan by a transamidase named sortase. Two genes encoding putative sortases, termed srtA and srtB, were(More)
Transcriptomic analyses during growth in Luria-Bertani medium were performed in strain SL1344 of Salmonella enterica serovar Typhimurium and in two isogenic derivatives lacking Dam methylase. More genes were repressed than were activated by Dam methylation (139 versus 37). Key genes that were differentially regulated by Dam methylation were verified(More)
Mutants of Salmonella enterica serovar Typhimurium lacking DNA adenine (Dam) methylase show reduced secretion of invasion effectors encoded in the Salmonella-pathogenicity island 1 (SPI-1). Concomitant with this alteration, a high number and quantity of extracellular proteins are detected in cultures of Dam(-) mutants. This study shows by subcellular(More)
Bacterial pathogenesis relies on regulators that activate virulence genes. Some of them act, in addition, as repressors of specific genes. Intracellular-growth-attenuator-A (IgaA) is a Salmonella enterica membrane protein that prevents overactivation of the RcsC-YojN-RcsB regulatory system. This negative control is critical for growth because disruption of(More)
Sortases are enzymes that anchor surface proteins to the cell wall of Gram-positive bacteria by cleaving a sorting motif located in the C-terminus of the protein substrate. The best-characterized motif is LPXTG, which is cleaved between the T and G residues. In this study, a non-gel proteomic approach was used to identify surface proteins recognized by the(More)
Salmonella interact with eucaryotic membranes to trigger internalization into non-phagocytic cells. In this study we examined the distribution of host plasma membrane proteins during S. typhimurium invasion of epithelial cells. Entry of S. typhimurium into HeLa epithelial cells produced extensive aggregation of cell surface class I MHC heavy chain, beta(More)
Bacteria of the genus Listeria contain the largest family of LPXTG surface proteins covalently anchored to the peptidoglycan. The extent to which these proteins may function or be regulated cooperatively is at present unknown. Because of their unique cellular location, we reasoned that distinct LPXTG proteins could act as elements contributing to cell wall(More)
Gram-positive bacteria of the genus Listeria contain many surface proteins covalently bound to the peptidoglycan. In the pathogenic species Listeria monocytogenes, some of these surface proteins mediate adhesion and entry into host cells. Specialized enzymes called sortases anchor these proteins to the cell wall by a mechanism involving processing and(More)
For nearly 3 decades, listeriologists and immunologists have used mainly three strains of the same serovar (1/2a) to analyze the virulence of the bacterial pathogen Listeria monocytogenes. The genomes of two of these strains, EGD-e and 10403S, were released in 2001 and 2008, respectively. Here we report the genome sequence of the third reference strain,(More)