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Infect Immun, May 1998, p. 2245-2255, Vol. 66, No. 5
Department of Microbiology, College of
Physicians and Surgeons of Columbia University, New York, New York
10032
Received 29 October 1997/Returned for modification 4 December
1997/Accepted 12 February 1998
Previously, a collection of mutants of Legionella
pneumophila that had lost the ability to multiply within and kill
human macrophages was generated by Tn903dIIlacZ
transposon mutagenesis and classified into DNA hybridization groups. A
subset of these mutants was complemented by a plasmid, pMW100,
containing a 13.5-kb genomic DNA insert. This plasmid restored the
ability to multiply within and produce cytopathic effects on human
macrophages to members of DNA hybridization groups II, IV, VI, and
XVII. A region of the genomic insert of pMW100 was sequenced, and eight
potential genes were identified and named icmE,
icmG, icmC, icmD, icmJ, icmB, icmF, and tphA. None of the
genes encode potential protein products with significant homology to
previously characterized proteins, except for tphA, whose
product has significant homology to a family of
metabolite/H+ symport proteins from gram-negative bacteria.
The positions of the Tn903dIIlacZ insertions
within the genes were determined by nucleotide sequencing. No
Tn903dIIlacZ insertions mapped to
icmG, icmJ, or tphA; therefore,
these loci were mutated to test whether they were required for
macrophage killing. Complementation analysis was used to evaluate the
roles of the potential gene products and provide information on the
organization of transcriptional units within the region. The results
indicate that all identified open reading frames except
tphA are required for killing of human macrophages.
0019-9567/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
The Legionella pneumophila icmGCDJBF
Genes Are Required for Killing of Human Macrophages
*
Corresponding author. Mailing address: Department of
Microbiology, College of Physicians and Surgeons of Columbia
University, 701 West 168th St., New York, NY 10032. Phone: (212)
305-6913. Fax: (212) 305-1468. E-mail:
shuman{at}cuccfa.ccc.columbia.edu.
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