Metabolism of myo-Inositol by Legionella pneumophila Promotes Infection of Amoebae and Macrophages.
نویسندگان
چکیده
UNLABELLED Legionella pneumophila is a natural parasite of environmental amoebae and the causative agent of a severe pneumonia termed Legionnaires' disease. The facultative intracellular pathogen employs a bipartite metabolism, where the amino acid serine serves as the major energy supply, while glycerol and glucose are mainly utilized for anabolic processes. The L. pneumophila genome harbors the cluster lpg1653 to lpg1649 putatively involved in the metabolism of the abundant carbohydrate myo-inositol (here termed inositol). To assess inositol metabolism by L. pneumophila, we constructed defined mutant strains lacking lpg1653 or lpg1652, which are predicted to encode the inositol transporter IolT or the inositol-2-dehydrogenase IolG, respectively. The mutant strains were not impaired for growth in complex or defined minimal media, and inositol did not promote extracellular growth. However, upon coinfection of Acanthamoeba castellanii, the mutants were outcompeted by the parental strain, indicating that the intracellular inositol metabolism confers a fitness advantage to the pathogen. Indeed, inositol added to L. pneumophila-infected amoebae or macrophages promoted intracellular growth of the parental strain, but not of the ΔiolT or ΔiolG mutant, and growth stimulation by inositol was restored by complementation of the mutant strains. The expression of the Piol promoter and bacterial uptake of inositol required the alternative sigma factor RpoS, a key virulence regulator of L. pneumophila Finally, the parental strain and ΔiolG mutant bacteria but not the ΔiolT mutant strain accumulated [U-(14)C6]inositol, indicating that IolT indeed functions as an inositol transporter. Taken together, intracellular L. pneumophila metabolizes inositol through the iol gene products, thus promoting the growth and virulence of the pathogen. IMPORTANCE The environmental bacterium Legionella pneumophila is the causative agent of a severe pneumonia termed Legionnaires' disease. The opportunistic pathogen replicates in protozoan and mammalian phagocytes in a unique vacuole. Amino acids are thought to represent the prime source of carbon and energy for L. pneumophila However, genome, transcriptome, and proteome studies indicate that the pathogen not only utilizes amino acids as carbon sources but possesses broader metabolic capacities. In this study, we analyzed the metabolism of inositol by extra- and intracellularly growing L. pneumophila By using genetic, biochemical, and cell biological approaches, we found that L. pneumophila accumulates and metabolizes inositol through the iol gene products, thus promoting the intracellular growth, virulence, and fitness of the pathogen. Our study significantly contributes to an understanding of the intracellular niche of a human pathogen.
منابع مشابه
Cloning and characterization of the gene encoding the major cell-associated phospholipase A of Legionella pneumophila, plaB, exhibiting hemolytic activity.
Legionella pneumophila, the causative agent of Legionnaires' disease, is an intracellular pathogen of amoebae, macrophages, and epithelial cells. The pathology of Legionella infections involves alveolar cell destruction, and several proteins of L. pneumophila are known to contribute to this ability. By screening a genomic library of L. pneumophila, we found an additional L. pneumophila gene, pl...
متن کاملVirulence phenotypes of Legionella pneumophila associated with noncoding RNA lpr0035.
The Philadelphia-1 strain of Legionella pneumophila, the causative organism of Legionnaires' disease, contains a recently discovered noncoding RNA, lpr0035. lpr0035 straddles the 5' chromosomal junction of a 45-kbp mobile genetic element, pLP45, which can exist as an episome or integrated in the bacterial chromosome. A 121-bp deletion was introduced in strain JR32, a Philadelphia-1 derivative. ...
متن کاملLegionella pneumophila mip gene potentiates intracellular infection of protozoa and human macrophages.
Legionella pneumophila is an intracellular parasite of freshwater protozoa and human macrophages. Recent studies determined that the macrophage infectivity potentiator (Mip) surface protein, a prokaryotic homolog of the FK506-binding proteins, is required for optimal infection of macrophages. To determine whether Mip is also involved in L. pneumophila infection of protozoa, we examined the abil...
متن کامل2-Deoxy-D-glucose inhibits intracellular multiplication and promotes intracellular killing of Legionella pneumophila in A/J mouse macrophages.
Legionella pneumophila can grow intracellularly in A/J mouse macrophages. 2-Deoxy-D-glucose (2dG) (0.1, 1, and 10 mM) inhibited intracellular multiplication and promoted intracellular killing of L. pneumophila dose dependently when it was added to the culture medium of macrophage monolayers, whereas it did not inhibit the bacterial growth in buffered yeast extract broth, which was used for an L...
متن کاملbdhA-patD operon as a virulence determinant, revealed by a novel large-scale approach for identification of Legionella pneumophila mutants defective for amoeba infection.
Legionella pneumophila, the causative agent of Legionnaires' disease, is an intracellular parasite of eukaryotic cells. In the environment, it colonizes amoebae. After being inhaled into the human lung, the bacteria infect and damage alveolar cells in a way that is mechanistically similar to the amoeba infection. Several L. pneumophila traits, among those the Dot/Icm type IVB protein secretion ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Applied and environmental microbiology
دوره 82 16 شماره
صفحات -
تاریخ انتشار 2016