Coupling of “malic” enzyme and NADPH:NAD transhydrogenase in the energetics of Hymenolepis diminuta (Cestoda)

McKelvey, Jeffrey R.; Fioravanti, Carmen F.

doi:10.1016/0305-0491(84)90306-7

Cited by 10 publications

(7 citation statements)

References 12 publications

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“…This mitochondrial enzyme was functionally coupled to the 'malic enzyme' and is thus involved in the energy supply under anaerobic conditions [24]. A transhydrogenase has been described for the intestinal helminth Hyrnenolepis diminuta (Cestoda).…”

Section: Resultsmentioning

confidence: 99%

Eimeria refractile body proteins contain two potentially functional characteristics: Transhydrogenase and carbohydrate transport

Vermeulen¹

1993

FEMS Microbiology Letters

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cDNA encoding an immunogenic protein from partially sporulated oocysts of Eimeria acervulina was cloned and used to search for the homologous counterpart in Eimeria tenella. Monospecific antibodies were raised against the recombinant expression product. Using these antibodies, the parasite proteins were found to be localised in the refractile bodies. The derived amino-acid sequences were compared by computer using the SWISSPROT protein database. In addition to high homology between the Eimeria species, extensive similarity was found with pyridine nucleotide transhydrogenase from Escherichia coli. Comparison with the sugar signature database also resulted in a possible sugar binding domain present only in the Eimeria proteins. It is possible that the corresponding parasite proteins play a role in the recently discovered mannitol cycle of Eimeria.

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Section: Resultsmentioning

confidence: 99%

Eimeria refractile body proteins contain two potentially functional characteristics: Transhydrogenase and carbohydrate transport

Vermeulen¹

1993

FEMS Microbiology Letters

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“…Cytosolic malate then serves as the mitochondrial substrate. Upon entering the mitochondrial matrix, malate is oxidatively decarboxylated by the NADP-specific ‘malic’ enzyme, thereby yielding pyruvate, CO 2 and reducing power for electron transport in the form of NADPH (Prescott and Campbell, 1965; Li et al 1972; Saz et al 1972; McKelvey and Fioravanti, 1984, 1985). Malate also is converted to fumarate by matrix fumarase (Read, 1953; McKelvey and Fioravanti, 1985).…”

Section: Energetic Metabolism Of Adult Hymenolepis Diminutamentioning

confidence: 99%

“…With respect to fumarate-dependent succinate formation, the coupling of the NADPH→NAD + transhydrogenase with fumarate reduction by H. diminuta mitochondrial membranes is essentially unchanged whether assessed under aerobic conditions or conditions of reduced oxygen tension (Fioravanti, 1981) (Table 1). Additionally, coupling of malate utilization with the H. diminuta electron transport system, via the NADPH→NAD + transhydrogenase, was demonstrated (McKelvey and Fioravanti, 1984).…”

Section: The Hymenolepis Diminuta Mitochondrial Nadph→nad+ Systemmentioning

confidence: 99%

Transhydrogenase and the anaerobic mitochondrial metabolism of adultHymenolepis diminuta

Fioravanti

Vandock

2009

Parasitology

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The adult cestode, Hymenolepis diminuta, is essentially anaerobic energetically. Carbohydrate dissimilation results in acetate, lactate and succinate accumulation with succinate being the major end product. Succinate accumulation results from the anaerobic, mitochondrial, 'malic' enzyme-dependent utilization of malate coupled to ATP generation via the electron transport-linked fumarate reductase. A lesser peroxide-forming oxidase is apparent, however, fumarate reduction to succinate predominates even in air. The H. diminuta matrix-localized 'malic' enzyme is NADP-specific whereas the inner membrane (IM)-associated electron transport system prefers NADH. This dilemma is circumvented by the mitochondrial, IM-associated NADPH-->NAD+ transhydrogenase in catalyzing hydride ion transfer from NADPH to NAD+ on the IM matrix surface. Hydride transfer is reversible and phospholipid-dependent. NADP+ reduction occurs as a non energy-linked and energy-linked reaction with the latter requiring electron transport NADH utilization or ATP hydrolysis. With NAD+ reduction, the cestode transhydrogenase also engages in concomitant proton translocation from the mitochondrial matrix to the intermembrane space and supports net ATP generation. Thus, the cestode NADPH-->NAD+ system can serve not only as a metabolic connector, but an additional anaerobic phosphorylation site. Although its function(s) is unknown, a separate IM-associated NADH--> NAD+ transhydrogenation, catalyzed by the lipoamide and NADH dehydrogenases, is noted.

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“…Malate is also converted to fumarate by fumarase (Scheibel and Saz 1966;Scheibel et al 1968). Reducing equivalents, arising from NADPH, serve to complete the dismutation with the reduction of fumarate to succinate by electron-transportcoupled, ATP-generating fumarate reductase (FR) (Saz et al 1972;McKelvey and Fioravanti 1984). Inasmuch as the H. diminuta FR employs NADH as the reductant, a need for hydride ion transfer from NADPH to NAD + to form NADH is apparent (Saz et al 1972;Fioravanti 1981).…”

Section: Introductionmentioning

confidence: 99%

Catalysis of NADH→NADP+ transhydrogenation by adult Hymenolepis diminuta mitochondria

Park

Fioravanti

2005

Parasitol Res

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Hymenolepis diminuta mitochondria catalyze nonenergy-linked and energy-linked NADH-->NADP(+) transhydrogenations, with the latter driven by electron-transport dependent NADH oxidation (electron transport-driven, ETD) or ATP hydrolysis (ATP-driven, ATPD). Using submitochondrial particles, NADH-->NADP(+) transhydrogenations were characterized further. ETD and ATPD reactions were enhanced by bovine serum albumin (BSA) and were inhibited by N,N'-dicyclohexylcarbodiimide (DCCD), carbonyl cyanide 3-chlorophenylhydrazone (CCCP), carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), and niclosamide. The nonenergy-linked reaction was unaffected by these additives. Except for DCCD inhibition of the ATPD reaction, BSA mitigated inhibitor effects on energy-linked activities. BSA enhanced NADH oxidase (but not ATPase) activity. Although DCCD inhibited NADH oxidase and ATPase, BSA only lessened oxidase inhibition. With protonophores, an increase in NADH oxidase (but not ATPase) activity was suggested. Oxidase inhibition by rotenone was unaffected by BSA. The ATP-hydrolyzed/NADPH-formed for the ATPD reaction was almost unity. A model for H. diminuta energy-linked transhydrogenation is presented.

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Coupling of “malic” enzyme and NADPH:NAD transhydrogenase in the energetics of Hymenolepis diminuta (Cestoda)

Cited by 10 publications

References 12 publications

Eimeria refractile body proteins contain two potentially functional characteristics: Transhydrogenase and carbohydrate transport

Eimeria refractile body proteins contain two potentially functional characteristics: Transhydrogenase and carbohydrate transport

Transhydrogenase and the anaerobic mitochondrial metabolism of adultHymenolepis diminuta

Catalysis of NADH→NADP+ transhydrogenation by adult Hymenolepis diminuta mitochondria

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