Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.3 (complex I)
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Anabaena sp. PCC7120 contains a gene, mrpA (all1838), which forms part of a seven gene-cluster (all1843-all1837) with significant sequence similarity to bacterial operons that putatively code for a multicomponent cation/proton antiporter involved in alkaline pH adaptation and salt resistance. We previously showed that growth and photosynthesis were inhibited in a strain mutated in mrpA, denoted as PHB11, particularly at alkaline pH. Here, we show that respiration was also impaired in the mutant independently of the external pH. In addition, at high pH, less ATP and vegetative cell ferredoxin were present in PHB11, which also showed lower levels of ferredoxin-NADP(+) oxidoreductase (FNR). Ferredoxin and FNR are involved in the generation of reductant NADPH in cyanobacteria. These results suggest an energetic role of mrpA (and perhaps of the whole mrp-gene cluster) in Anabaena sp. PCC 7120 that is further supported by the significant similarity of putative Anabaena Mrp proteins to membrane subunits of complex I.
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PMID:mrpA (all1838), a gene involved in alkali and Na(+) sensitivity, may also have a role in energy metabolism in the cyanobacterium Anabaena sp. strain PCC 7120. 1941 Mar 33

Although type-1 NAD(P)H dehydrogenase (NDH) complex subunit constituents and physiological functions have been reported in plants and cyanobacteria, the biochemical properties of this enzyme are not clear. We used chromatographic isolation to purify and characterize a NADPH-active NDH from the cyanobacterium Thermosynechococcus elongatus. Ferredoxin (Fd) and ferredoxin-NADP(+) oxidoreductase (FNR) were co-eluted with NDH, implying the electron donation from NADPH to NDH via the interaction with FNR. We investigated the enzymatic properties of the complex. Furthermore, the activity is competitively inhibited by rotenone, suggesting that it possesses a quinone binding site, similar to mitochondria complex I.
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PMID:Enzymatic characterization of an active NDH complex from Thermosynechococcus elongatus. 2372 12