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- Title
Five Listeria monocytogenes genes preferentially expressed in infected mammalian cells: pIcA, purH, purD, pyrE and an arginine ABC transporter gene, arpJ.
- Authors
Klarsfeld, Andre D.; Goossens, Pierre L.; Cossart, Pascale
- Abstract
<em>Listeria monocytogenes</em> is a bacterial pathogen that multiplies within the cytosol of eukaryotic cells. To identify Listeria genes with preferentially intracellular expression (<em>pic</em> genes), a library of Tn<em>917-lac</em> insertion mutants was screened for transcriptional fusions to <em>lacZ</em> with higher expression inside a macrophagelike cell line than in a rich broth medium. Five pic genes with up to 100-fold induction inside cells were identified. Three of them (<em>purH, purD and pyrE</em>) were involved in nucleotide biosynthesis. One was part of an operon encoding an ABC (ATP-binding cassette) transporter for arginine. The corresponding mutants were not affected in intracellular growth, cell-to-cell spread or virulence, except for the transporter mutant, whose LD50 after intravenous infection of mice was twofold higher than the wild-type. The fifth gene was <em>plcA</em>, a previously identified virulence gene that encodes a phosphatidylinositol-phospholipase C, and is cotranscritied with <em>prfA</em>, a gene encoding a pleiotropic transcriptional activator of known virulence genes. Although <em>plcA</em> expression is known to depend on PrfA, a <em>prfA</em> promoter-<em>lacZ</em> fusion was highly expressed both inside and outside cells. Furthermore, in the presence of cellobiose, a disaccharide recently shown to repress <em>plcA</em> and <em>hly</em> expression, <em>plcA</em> and <em>hly</em> mRNA levels were dramatically reduced without any decrease in the monocistronic <em>prfA</em> mRNA levels. These results demonstrate that virulence gene activation does not depend only on <em>prfA</em> transcript accumulation.
- Subjects
LISTERIA monocytogenes; LISTERIA; BACTERIA; PATHOGENIC microorganisms; CYTOSOL; EUKARYOTIC cells; GENES
- Publication
Molecular Microbiology, 1994, Vol 13, Issue 4, p585
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.1994.tb00453.x