Cadmium-sensitive targets in the aerobic respiratory metabolism of Staphylococcus aureus.
In: Journal of basic microbiology, Jg. 36 (1996), Heft 6, S. 447-52
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Zugriff:
Studies on the effect of various Cd2+ concentrations on substrate oxidation by whole cells of cadmium-sensitive Staphylococcus aureus 17810S showed that oxidation of glutamate or pyruvate was highly sensitive to low Cd2+ concentrations (5 microM), whereas L-lactate oxidation was insensitive even to high Cd2+ concentrations (100 microM). Location of the cadmium-sensitive targets in the enzyme systems involved in oxidation of these substrates was studied in subcellular fractions prepared from cells pretreated with 5 or 100 microM Cd2+. Activities of the cytoplasmic 2-oxoglutarate dehydrogenase complex (ODHC)') and pyruvate dehydrogenase complex (PDHC) were strongly inhibited with 5 microM Cd2+, while with 100 microM Cd2+ the inhibition was almost complete. In contrast, activities of the cytoplasmic NAD-dependent glutamate dehydrogenase (NAD-GDH), the membrane-bound NADH dehydrogenase (NDH) and HQNO-sensitive NADH oxidase were not sensitive to 100 microM Cd2+. These data indicate that the accessible, cadmium-sensitive targets are located only in the cytoplasmic ODHC and PDHC. It is postulated that two vicinal dithiols present in ODHC and PDHC may be regarded as the primary cadmium-sensitive targets in the systems oxidizing glutamate or pyruvate. Since activities of the membrane-bound NAD-independent L-lactate dehydrogenase (iLDH) and HQNO-sensitive L-lactate oxidase were not affected by 100 microM Cd2+, this indicates that the L-lactate oxidizing system lacks the accessible, cadmium-sensitive targets. The mechanism of Cd2+ toxicity to energy conservation with glutamate, pyruvate or L-lactate in S. aureus is discussed.
Titel: |
Cadmium-sensitive targets in the aerobic respiratory metabolism of Staphylococcus aureus.
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Autor/in / Beteiligte Person: | Tynecka, Z ; Malm, A |
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Zeitschrift: | Journal of basic microbiology, Jg. 36 (1996), Heft 6, S. 447-52 |
Veröffentlichung: | <2005->: Weinheim, Germany : Wiley-VCH Verlag ; <i>Original Publication</i>: Berlin : Akademie-Verlag, [1985-, 1996 |
Medientyp: | academicJournal |
ISSN: | 0233-111X (print) |
DOI: | 10.1002/jobm.3620360610 |
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