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Alternative NADH dehydrogenase (NDH2): intermembrane-space-facing counterpart of mitochondrial complex I in the procyclic Trypanosoma brucei

The respiratory chain of the procyclic stage of Trypanosoma brucei contains the standard complexes I through IV, as well as several alternative enzymes contributing to electron flow. In this work, we studied the function of an alternative NADH : ubiquinone oxidoreductase (NDH2). Depletion of target...

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Published in:Parasitology 2013-03, Vol.140 (3), p.328-337
Main Authors: VERNER, ZDENĚK, ŠKODOVÁ, INGRID, POLÁKOVÁ, SIMONA, ĎURIŠOVÁ-BENKOVIČOVÁ, VLADISLAVA, HORVÁTH, ANTON, LUKEŠ, JULIUS
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Language:English
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Summary:The respiratory chain of the procyclic stage of Trypanosoma brucei contains the standard complexes I through IV, as well as several alternative enzymes contributing to electron flow. In this work, we studied the function of an alternative NADH : ubiquinone oxidoreductase (NDH2). Depletion of target mRNA was achieved using RNA interference (RNAi). In the non-induced and RNAi-induced cell growth, membrane potential change, alteration in production of reactive oxygen species, overall respiration, enzymatic activities of complexes I, III and/or IV and distribution of NADH : ubiquinone oxidoreductase activities in glycerol gradient fractions were measured. Finally, respiration using different substrates was tested on digitonin-permeabilized cells. The induced RNAi cell line exhibited slower growth, decreased mitochondrial membrane potential and lower sensitivity of respiration to inhibitors. Mitochondrial glycerol-3-phosphate dehydrogenase was the only enzymatic activity that has significantly changed in the interfered cells. This elevation as well as a decrease of respiration using NADH was confirmed on digitonin-permeabilized cells. The data presented here together with previously published findings on complex I led us to propose that NDH2 is the major NADH : ubiquinone oxidoreductase responsible for cytosolic and not for mitochondrial NAD+ regeneration in the mitochondrion of procyclic T. brucei.
ISSN:0031-1820
1469-8161
1469-8161
DOI:10.1017/S003118201200162X