The mitochondrial respiratory chain of Rhizopus stolonifer (Ehrenb.:Fr.) Vuill
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ORIGINAL PAPER
The mitochondrial respiratory chain of Rhizopus stolonifer (Ehrenb.:Fr.) Vuill Leobarda Robles-Martı´nez • Marı´a Guadalupe Guerra-Sa´nchez Oscar Flores-Herrera • Ana Niurka Herna´ndez-Lauzardo • Miguel Gerardo Vela´zquez-Del Valle • Juan Pablo Pardo
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Received: 26 June 2012 / Revised: 13 September 2012 / Accepted: 15 September 2012 / Published online: 12 October 2012 Ó Springer-Verlag Berlin Heidelberg 2012
Abstract Rhizopus stolonifer (Ehrenb.:Fr.) Vuill mitochondria contain the complete system for oxidative phosphorylation, formed by the classical components of the electron transport chain (complexes I, II, III, and IV) and the F1F0-ATP synthase (complex V). Using the native gel electrophoresis, we have shown the existence of supramolecular associations of the respiratory complexes. The composition and stoichiometry of the oxidative phosphorylation complexes were similar to those found in other organisms. Additionally, two alternative routes for the oxidation of cytosolic NADH were identified: the alternative NADH dehydrogenase and the glycerol-3-phosphate shuttles. Residual respiratory activity after inhibition of complex IV by cyanide was inhibited by low concentrations of n-octyl gallate, indicating the presence of an alternative oxidase. The
Communicated by John Helman.
Electronic supplementary material The online version of this article (doi:10.1007/s00203-012-0845-7) contains supplementary material, which is available to authorized users. L. Robles-Martı´nez M. G. Guerra-Sa´nchez Departamento de Microbiologı´a, Escuela Nacional de Ciencias Biolo´gicas, Instituto Polite´cnico Nacional, Mexico, D. F., Mexico O. Flores-Herrera J. P. Pardo (&) Departamento de Bioquı´mica, Facultad de Medicina, Universidad Nacional Auto´noma de Me´xico, Apartado Postal 70-159, Coyoaca´n, 04510 Mexico, D. F., Mexico e-mail: [email protected] O. Flores-Herrera e-mail: [email protected] A. N. Herna´ndez-Lauzardo M. G. Vela´zquez-Del Valle CEPROBI, Instituto Polite´cnico Nacional, Yautepec, Morelos, Mexico
K0.5 for the respiratory substrates NADH, succinate, and glycerol-3-phosphate in permeabilized cells was higher than in isolated mitochondria, suggesting that interactions of mitochondria with other cellular elements might be important for the function of this organelle. Keywords Oxidative phosphorylation F1F0-ATP synthase Respiratory supercomplexes NADH dehydrogenase Glycerol-3-phosphate shuttle
Introduction Rhizopus soft rot caused by Rhizopus stolonifer (Ehrenb.:Fr.) Vuill is one of the most destructive postharvest storage diseases of fruits and vegetables (Snowdon 1992). Rhizopus stolonifer is a filamentous fungus characterized by the formation of rhizoids, sporangiophores, sporangiospores, and zygospores (Schipper 1984). Despite the economic importance of Rhizopus soft, very few studies on the metabolism have been carried out with R. stolonifer, and there are no reports on the structural organization of its mitochondrial respiratory chain. Most mitochondria contain the classic respiratory
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