Identification of migR, a regulatory element of the Francisella tularensis live vaccine strain iglABCD virulence operon required for normal replication and trafficking in macrophages
| Autor: | Bradley D. Jones, Lee-Ann H. Allen, Blake W. Buchan, Stephen R. Lindemann, Ramona L. McCaffrey |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Adult
Operon Neutrophils Virulence Factors Immunology Mutant Mutation Missense Mutagenesis (molecular biology technique) Microbiology Cell Line Young Adult Bacterial Proteins Phagosomes Humans Francisella tularensis Gene Cells Cultured Phagosome Regulation of gene expression Innate immune system biology Virulence Gene Expression Profiling Macrophages Gene Expression Regulation Bacterial biology.organism_classification Molecular Pathogenesis Infectious Diseases Amino Acid Substitution Mutagenesis Site-Directed Parasitology |
| Zdroj: | Infection and immunity. 77(6) |
| ISSN: | 1098-5522 |
| Popis: | Francisella tularensis, the etiological agent of tularemia, is capable of infecting a wide range of animals and causes a severe, lethal disease in humans. The pathogen evades killing by cells of the innate immune system utilizing genes encoding a pathogenicity island, includingiglABCD, and instead utilizes these cells as a niche for replication and dissemination to other organs within the host. Regulators of theiglgenes (e.g., MglA, SspA, FevR and PmrA) have been identified, but environmental stimuli and mechanisms of regulation are as yet unknown and are likely to involve additional gene products. In this work, we more closely examine the roles that environmental iron and the ferric uptake repressor protein (Fur) play in the regulation of theiglABCDoperon. We also used a genetic approach to identify and characterize a new regulator of theigloperon, designatedmigR(macrophageintracellulargrowthregulator; FTL_1542). Quantitative real-time reverse transcription-PCR in a site-directedmigRmutant confirmed the reduction in the number ofiglCtranscripts in this strain and also demonstrated reduced expression offevR. Comparison of themigRandfevRmutants in monocyte-derived macrophages (MDMs) and epithelial cell lines revealed a reduced ability for each mutant to grow in MDMs, yet only thefevRmutant exhibited impaired replication in epithelial cell lines. Confocal analysis of infected MDMs revealed that although neither mutant reached the MDM cytosol, thefevRmutant was trapped in lamp-1-positive phagosomes, whereas themigRmutant resided in mature phagolysosomes enriched with both lamp-1 and cathepsin D. Disruption ofmigRandfevRalso impaired the ability ofF. tularensisto prevent neutrophil oxidant production. Thus, we have identifiedmigR, a gene that regulates expression of theiglABCDoperon and is essential for bacterial growth in MDMs and also contributes to the blockade of neutrophil NADPH oxidase activity. |
| Databáze: | OpenAIRE |
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