Identification of linked Legionella pneumophila genes essential for intracellular growth and evasion of the endocytic pathway

被引:166
作者
Andrews, HL
Vogel, JP
Isberg, RR
机构
[1] Tufts Univ, Sch Med, Howard Hughes Med Inst, Dept Mol Biol & Microbiol, Boston, MA 02111 USA
[2] Tufts Univ, Sch Vet Med, Boston, MA 02111 USA
关键词
D O I
10.1128/IAI.66.3.950-958.1998
中图分类号
R392 [医学免疫学]; Q939.91 [免疫学];
学科分类号
100102 ;
摘要
Legionella pneumophila replicates within a specialized phagosome in cultured cells, a function necessary for its pathogenicity. The replicative phagosome lacks membrane marker proteins, such as the glycoprotein LAMP-1, that are indicators of the normal endocytic pathway. We describe the isolation of several Legionella genes essential for intracellular growth and evasion of the endocytic pathway, using a genetic and cell biological approach. We screened 4,960 ethyl methanesulfonate-mutagenized colonies for defects in intracellular growth and trafficking to the replicative phagosome. Six mutant strains of L. pneumophila that had severe intracellular growth defects in mouse bone marrow-derived macrophages were identified. All six mutants were found in phagosomes that colocalized with LAMP-1, indicating defects in intracellular trafficking. The growth defects of two of these strains were complemented by molecular clones from a bank constructed from a wild-type L. pneumophila strain. The inserts from these clones are located in a region of the chromosome contiguous with several other genes essential for intracellular growth. Three mutants could be complemented by single open reading frames placed in trans, one mutant by a gene termed dotH and two additional mutants by a gene termed dotO. A deletion mutation was created in a third gene, dotI, which is located directly upstream of dotH. The Delta dotI strain was also defective for intracellular growth in macrophages, and this defect was complemented bg a single open reading frame in trans. Based an sequence analysis and structural predictions, possible roles of dotH, dotI, and dotO in intracellular growth are discussed.
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页码:950 / 958
页数:9
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