Physiological relevance, localization and substrate specificity of the alternative (type II) mitochondrial NADH dehydrogenases of Ogataea parapolymorpha

Mitochondria from Ogataea parapolymorpha harbor a branched electron-transport chain containing a proton-pumping Complex I NADH dehydrogenase and three alternative (type II) NADH dehydrogenases (NDH2s). To investigate the physiological role, localization and substrate specificity of these enzymes, gr...

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Published inbioRxiv
Main Authors Juergens, Hannes, Mielgo-Gómez, Álvaro, Godoy-Hernández, Albert, Jolanda Ter Horst, Nijenhuis, Janine M, Mcmillan, Duncan G G, Mans, Robert
Format Paper
LanguageEnglish
Published Cold Spring Harbor Cold Spring Harbor Laboratory Press 28.04.2021
Subjects
Dehydrogenases
Electron transport chain
Localization
Metabolism
Mitochondria
NAD
NADH
NADH dehydrogenase
Oxidation
Physiology
Quinones
Substrate specificity
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Summary:Mitochondria from Ogataea parapolymorpha harbor a branched electron-transport chain containing a proton-pumping Complex I NADH dehydrogenase and three alternative (type II) NADH dehydrogenases (NDH2s). To investigate the physiological role, localization and substrate specificity of these enzymes, growth of various NADH dehydrogenase mutants was quantitatively characterized in shake-flask and chemostat cultures, followed by oxygen-uptake experiments with isolated mitochondria. Furthermore, NAD(P)H:quinone oxidoreduction of the three NDH2s were individually assessed. Our findings show that the O. parapolymorpha respiratory chain contains an internal NADH-accepting NDH2 (Ndh2-1/OpNdi1), at least one external NAD(P)H-accepting enzyme and likely additional mechanisms for respiration-linked oxidation of cytosolic NADH. Metabolic regulation appears to prevent competition between OpNdi1 and Complex I for mitochondrial NADH. With the exception of OpNdi1, the respiratory chain of O. parapolymorpha exhibits metabolic redundancy and tolerates deletion of multiple NADH-dehydrogenase genes without compromising fully respiratory metabolism. Competing Interest Statement The authors have declared no competing interest.
DOI:10.1101/2021.04.28.441406