期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
卷 1817, 期 2, 页码 353-362出版社
ELSEVIER
DOI: 10.1016/j.bbabio.2011.11.007
关键词
Yarrowia lipolytica; Mitochondrion; Branched respiratory chain; Alternative NADH dehydrogenase; Physiological uncoupling; Reactive oxygen species, ROS
资金
- [CONACYT 79989]
- [DGAPA UNAM IN217109]
- [CONACYT 128110]
- [DGAPA UNAM IN203311-3]
In the branched mitochondrial respiratory chain from Yarrowia lipolytica there are two alternative oxidoreductases that do not pump protons, namely an external type II NADH dehydrogenase (NDH2e) and the alternative oxidase (AOX). Direct electron transfer between these proteins is not coupled to ATP synthesis and should be avoided in most physiological conditions. However, under low energy-requiring conditions an uncoupled high rate of oxygen consumption would be beneficial, as it would prevent overproduction of reactive oxygen species (ROS). In mitochondria from high energy-requiring, logarithmic-growth phase cells, most NDH2e was associated to cytochrome c oxidase and electrons from NADH were channeled to the cytochromic pathway. In contrast, in the low energy requiring, late stationary-growth phase, complex IV concentration decreased, the cells overexpressed NDH2e and thus a large fraction of this enzyme was found in a non-associated form. Also, the NDH2e-AOX uncoupled pathway was activated and the state IV external NADH-dependent production of ROS decreased. Association/dissociation of NDH2e to/from complex IV is proposed to be the switch that channels electrons from external NADH to the coupled cytochrome pathway or allows them to reach an uncoupled, alternative. Delta Psi-independent pathway. (C) 2011 Elsevier B.V. All rights reserved.
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