Role of RelGsuin Stress Response and Fe(III) Reduction inGeobacter sulfurreducens
| Autor: | Barbara A. Methé, Laurie N. DiDonato, Derek R. Lovley, Sara A. Sullivan, Reg England, Kelly P. Nevin |
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| Rok vydání: | 2006 |
| Předmět: |
Physiology and Metabolism
Mutant Guanosine Guanosine Tetraphosphate Ferric Compounds Microbiology Ligases chemistry.chemical_compound Bacterial Proteins Heat shock Molecular Biology Geobacter sulfurreducens Oligonucleotide Array Sequence Analysis biology Strain (chemistry) Reverse Transcriptase Polymerase Chain Reaction Wild type Gene Expression Regulation Bacterial biology.organism_classification Culture Media chemistry Biochemistry Mutation Geobacter Oxidation-Reduction Heat-Shock Response Sulfur Bacteria |
| Zdroj: | Journal of Bacteriology. 188:8469-8478 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.01278-06 |
| Popis: | Geobacterspecies are key members of the microbial community in many subsurface environments in which dissimilatory metal reduction is an important process. The genome ofGeobacter sulfurreducenscontains a gene designatedrelGsu, which encodes a RelA homolog predicted to catalyze both the synthesis and the degradation of guanosine 3′,5′-bispyrophosphate (ppGpp), a regulatory molecule that signals slow growth in response to nutrient limitation in bacteria. To evaluate the physiological role of RelGsuinG. sulfurreducens, arelGsumutant was constructed and characterized, and ppGpp levels were monitored under various conditions in both the wild-type andrelGsumutant strains. In the wild-type strain, ppGpp and ppGp were produced in response to acetate and nitrogen deprivation, whereas exposure to oxygen resulted in an accumulation of ppGpp alone. Neither ppGpp nor ppGp could be detected in therelGsumutant. TherelGsumutant consistently grew to a higher cell density than the wild type in acetate-fumarate medium and was less tolerant of oxidative stress than the wild type. The capacity for Fe(III) reduction was substantially diminished in the mutant. Microarray and quantitative reverse transcription-PCR analyses indicated that during stationary-phase growth, protein synthesis genes were up-regulated in therelGsumutant and genes involved in stress responses and electron transport, including several implicated in Fe(III) reduction, were down-regulated in the mutant. The results are consistent with a role for RelGsuin regulating growth, stress responses, and Fe(III) reduction inG. sulfurreducensunder conditions likely to be prevalent in subsurface environments. |
| Databáze: | OpenAIRE |
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