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M M Brett - One of the best experts on this subject based on the ideXlab platform.

Tadahiro Karasawa - One of the best experts on this subject based on the ideXlab platform.

Emi Temaru - One of the best experts on this subject based on the ideXlab platform.

Pascale Cossart - One of the best experts on this subject based on the ideXlab platform.

  • nucleotide sequence of the Lecithinase operon of listeria monocytogenes and possible role of Lecithinase in cell to cell spread
    Infection and Immunity, 1992
    Co-Authors: Jose A Vazquezboland, Christine Kocks, Shaynoor Dramsi, Helene Ohayon, C Geoffroy, J Mengaud, Pascale Cossart
    Abstract:

    The Lecithinase gene of the intracellular pathogen Listeria monocytogenes, plcB, was identified in a 5,648-bp DNA fragment which expressed Lecithinase activity when cloned into Escherichia coli. This fragment is located immediately downstream of the previously identified gene mpl (prtA). It contains five open reading frames, named actA, plcB, and ORFX, -Y, and -Z, which, together with mpl, form an operon, since a 5.7-kb-long transcript originates from a promoter located upstream of mpl (J. Mengaud, C. Geoffroy, and P. Cossart, Infect. Immun. 59:1043-1049, 1991). A second promoter was detected in front of actA which encodes a putative membrane protein containing a region of internal repeats. plcB encodes the Lecithinase, a predicted 289-amino-acid protein homologous to the phosphatidylcholine-specific phospholipases C of Bacillus cereus and Clostridium perfringens (alpha-toxin). plcB mutants produce only small plaques on fibroblast monolayers, and an electron microscopic analysis of infected macrophages suggests that Lecithinase is involved in the lysis of the two-membrane vacuoles that surround the bacteria after cell-to-cell spread. On the opposite DNA strand, downstream of the operon, three more open reading frames, ldh, ORFA, and ORFB, were found. The deduced amino acid sequence of the first one is homologous to lactate dehydrogenases. Low-stringency Southern hybridization experiments suggest that these three open reading frames lie outside of the L. monocytogenes virulence region: mpl and actA were specific for L. monocytogenes, sequences hybridizing to plcB were detected in L. ivanovii and L. seeligeri, and sequences hybridizing to ORFX, -Y, and -Z were found in L. innocua. In contrast to this, sequences hybridizing to ldh or ORFB were detected in all Listeria species (including the nonpathogenic ones).

James B Kaper - One of the best experts on this subject based on the ideXlab platform.

  • cloning characterization and chromosomal mapping of a phospholipase Lecithinase produced by vibrio cholerae
    Infection and Immunity, 1997
    Co-Authors: Anthony E Fiore, Jane Michalski, R G Russell, Cynthia L Sears, James B Kaper
    Abstract:

    Phospholipases are associated with virulence in bacterial diseases. Vibrio cholerae produces a phospholipase (Lecithinase), with enzyme production visualized as a zone of clearing around colonies plated on egg yolk agar. The role of phospholipase in gut colonization or disease pathogenesis is unknown. We used the egg yolk agar assay to clone and characterize a gene encoding a phospholipase from V. cholerae El Tor strain E7946. Sequence analysis revealed a 1,254-bp open reading frame (lec) encoding a 418-amino-acid protein with a predicted molecular weight of 47,600. The predicted sequence exhibits DNA homology to other Vibrionaceae phospholipases. A potential signal sequence exists in the predicted amino acid sequence, as does a lipid binding motif found in prokaryotic and eukaryotic phospholipases and lipases. Polyacrylamide gel electrophoresis combined with an egg yolk agarose overlay demonstrated phospholipase activity migrating at a relative molecular weight of 45,000 in preparations of V. cholerae and the Escherichia coli clone. Restriction mapping and Southern blot analysis revealed that lec, hlyA (hemolysin), and hlyC (lipase) are adjacent on the V. cholerae chromosome, and chromosomal digests of several El Tor, classical, and O139 (Bengal) strains demonstrated conservation of this gene arrangement. An in-frame internal deletion of the lec gene was constructed and recombined into the chromosome of attenuated V. cholerae El Tor strain CVD 110. The resulting mutant lacked Lecithinase activity on egg yolk agar but had undiminished reactivity in rabbit ligated ileal loop assays.