1. Contribution of Complex I NADH dehydrogenase to respiratory energy coupling in glucose-grown cultures of Ogataea parapolymorpha.
- Author
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Juergens, Hannes, Hakkaart, Xavier D. V., Bras, Jildau E., Vente, André, Liang Wu, Benjamin, Kirsten R., Pronk, Jack T., Daran-Lapujade, Pascale, and Mans, Robert
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NADH dehydrogenase , *PROTEOMICS , *NAD (Coenzyme) , *AEROBIC metabolism , *LIGNOCELLULOSE , *DEHYDROGENASES , *SUGAR - Abstract
The thermotolerant yeast Ogataea parapolymorpha (formerly Hansenula polymorpha) is an industrially relevant production host that exhibits a fully respiratory sugar metabolism in aerobic batch cultures. NADH-derived electrons can enter its mitochondrial respiratory chain either via a proton-translocating Complex I NADH-dehydrogenase or via three putative alternative NADH dehydrogenases. This respiratory entry point affects the amount of ATP produced per NADH/O2 consumed and therefore impacts the maximum yield of biomass and/or cellular products from a given amount of substrate. To investigate the physiological importance of Complex I, a wild-type O. parapolymorpha strain and a congenic Complex I-deficient mutant were grown on glucose in aerobic batch, chemostat and retentostat cultures in bioreactors. In batch cultures, both strains exhibited a fully respiratory metabolism and showed the same growth rate and biomass yield, indicating that, under these conditions, the contribution of NADH oxidation via Complex I was negligible. Both strains also exhibited a respiratory metabolism in glucose-limited chemostat cultures, but the Complex I-deficient mutant showed considerably reduced biomass yields on substrate and oxygen, consistent with a lower efficiency of respiratory energy coupling. In glucose-limited retentostat cultures at specific growth rates down to ~0.001 h-1, both O. parapolymorpha strains showed a high viability. Maintenance-energy requirements at these extremely low growth rates were approximately 3-fold lower than estimated from faster-growing chemostat cultures, indicating a 'stringent response'-like behavior. Quantitative transcriptome and proteome analyses indicated condition39 dependent expression patterns of Complex I subunits and of alternative NADH dehydrogenases that were consistent with physiological observations. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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