Identification of Functional Tat Signal Sequences in Mycobacterium tuberculosis Proteins
| Autor: | Nathan W. Rigel, Jason S. Silverman, Erin McElvania TeKippe, Justin A. McDonough, Miriam Braunstein, Jessica R. McCann |
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| Rok vydání: | 2008 |
| Předmět: |
Signal peptide
In silico Immunoblotting Biology Arginine Microbiology Mycobacterium tuberculosis Twin-arginine translocation pathway Open Reading Frames Bacterial Proteins Molecular Biology Molecular Biology of Pathogens Models Genetic Membrane transport protein Mycobacterium smegmatis Membrane Transport Proteins biology.organism_classification Molecular biology Cell biology Transport protein Protein Transport Type C Phospholipases biology.protein Signal transduction Plasmids Signal Transduction |
| Zdroj: | Journal of Bacteriology. 190:6428-6438 |
| ISSN: | 1098-5530 0021-9193 |
| Popis: | The twin-arginine translocation (Tat) pathway is a system used by some bacteria to export proteins out from the cytosol to the cell surface or extracellular environment. A functional Tat pathway exists in the important human pathogen Mycobacterium tuberculosis . Identification of the substrates exported by the Tat pathway can help define the role that this pathway plays in the physiology and pathogenesis of M. tuberculosis . Here we used a reporter of Tat export, a truncated β-lactamase, ′BlaC, to experimentally identify M. tuberculosis proteins with functional Tat signal sequences. Of the 13 proteins identified, one lacks the hallmark of a Tat-exported substrate, the twin-arginine dipeptide, and another is not predicted by in silico analysis of the annotated M. tuberculosis genome. Full-length versions of a subset of these proteins were tested to determine if the native proteins are Tat exported. For three proteins, expression in a Δ tat mutant of Mycobacterium smegmatis revealed a defect in precursor processing compared to expression in the wild type, indicating Tat export of the full-length proteins. Conversely, two proteins showed no obvious Tat export in M. smegmatis . One of this latter group of proteins was the M. tuberculosis virulence factor phospholipase C (PlcB). Importantly, when tested in M. tuberculosis a different result was obtained and PlcB was exported in a twin-arginine-dependent manner. This suggests the existence of an M. tuberculosis -specific factor(s) for Tat export of a proven virulence protein. It also emphasizes the importance of domains beyond the Tat signal sequence and bacterium-specific factors in determining if a given protein is Tat exported. |
| Databáze: | OpenAIRE |
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