The H(+)-pyrophosphatase of Rhodospirillum rubrum is predominantly located in polyphosphate-rich acidocalcisomes
| Autor: | Manfredo J. Seufferheld, Christopher R. Lea, Mauricio Vieira, Roberto Docampo, Eric Oldfield |
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| Rok vydání: | 2004 |
| Předmět: |
Magnetic Resonance Spectroscopy
Blotting Western chemistry.chemical_element Calcium Rhodospirillum rubrum Biochemistry Pyrophosphate chemistry.chemical_compound Microscopy Electron Transmission Polyphosphates Triiodobenzoic Acids Extracellular Pyrophosphatases Microscopy Immunoelectron Molecular Biology Microscopy Confocal Perchlorates biology Dose-Response Relationship Drug Polyphosphate X-Rays Cell Membrane Cell Biology Bacterial Chromatophores Hydrogen-Ion Concentration biology.organism_classification Cellular Structures Acidocalcisome Diphosphates Inorganic Pyrophosphatase Microscopy Electron Membrane chemistry Microscopy Fluorescence Protons Bacteria |
| Zdroj: | The Journal of biological chemistry. 279(49) |
| ISSN: | 0021-9258 |
| Popis: | Acidocalcisomes are acidic, calcium storage compartments with a H(+) pump located in their membrane that have been described in several unicellular eukaryotes, including trypanosomatid and apicomplexan parasites, algae, and slime molds, and have also been found in the bacterium Agrobacterium tumefaciens. In this work, we report that the H(+)-pyrophosphatase (H(+)-PPase) of Rhodospirillum rubrum, the first enzyme of this type that was identified and thought to be localized only to chromatophore membranes, is predominantly located in acidocalcisomes. The identification of the acidocalcisomes of R. rubrum was carried out by using transmission electron microscopy, x-ray microanalysis, and immunofluorescence microscopy. Purification of acidocalcisomes using iodixanol gradients indicated co-localization of the H(+)-PPase with pyrophosphate (PPi) and short and long chain polyphosphates (polyPs) but a lack of markers of the plasma membrane. polyP was also localized to the acidocalcisomes by using 4',6'-diamino-2-phenylindole staining and identified by using 31P NMR and biochemical methods. Calcium in the acidocalcisomes increased when the bacteria were incubated at high extracellular calcium concentrations. The number of acidocalcisomes and chromatophore membranes as well as the amounts of PPi and polyP increased when bacteria were grown in the light. Taken together, these results suggest that the H(+)-PPase of R. rubrum has two distinct roles depending on its location acting as an intracellular proton pump in acidocalcisomes but in PPi synthesis in the chromatophore membranes. |
| Databáze: | OpenAIRE |
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