Menaquinone is an obligatory component of the chain catalyzing succinate respiration in Bacillus subtilis |
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Authors: | Elena Lemma Gottfried Unden Achim Kröger |
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Institution: | (1) Institut für Mikrobiologie der J. W. Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, Haus 75A, W-6000 Frankfurt am Main, Federal Republic of Germany |
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Abstract: | The question was investigated as to whether the bacterial menaquinone (MK) is a component of the electron transport chain catalyzing succinate respiration in Bacillus subtilis. Three different methods were applied, and the following consistent results were obtained. (i) Solvent extraction of MK from the bacterial membrane caused total inhibition of the respiratory activities with succinate and NADH, while the activity of succinate dehydrogenase remained unaffected. The respiratory activities were restored onincorporation of vitamin K1 into the membrane preparation. (ii) The membrane fraction of a B. subtilis mutant containing 15% of the wild-type amount of MK, respired succinate and NADH at reduced activities. Wild-type activities were restored on fusion of the preparation to liposomes containing vitamin K1. (iii) The membrane fraction of B. subtilis catalyzed succinate oxidation by various water-soluble naphtho- or benzoquinones at specific activities exceeding to that of succinate respiration. The results suggest that MK is involved in succinate respiration, although its redox potential is unfavorable.Abbreviations MK
menaquinone
- MKH2
reduced menaquinone
- E0'
standard redox potential at pH 7
- PMS
phenazine methosulfate
- DCPIP
2,6-Dichlorophenol-indophenol
- Q
ubiquinone
- Q0
2,3-dimethoxy-5-methyl-1,4-bezoquinone
- DMN, 2,3
dimethyl-1,4-naphthoquinone
- DMK
demethylmenaquinone |
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Keywords: | Menaquinone Succinate respiration Electron transport Bacillus subtilis |
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