Welchen 2012 Biochim Biophys Acta

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Welchen E, Hildebrandt TM, Lewejohann D, Gonzalez DH, Braun HP (2012) Lack of cytochrome c in Arabidopsis decreases stability of Complex IV and modifies redox metabolism without affecting Complexes I and III. Biochim Biophys Acta 1817:990-1001.


Welchen E, Hildebrandt TM, Lewejohann D, Gonzalez DH, Braun HP (2012) Biochim Biophys Acta

Abstract: We studied the role of cytochrome c (CYTc), which mediates electron transfer between Complexes III and IV, in cellular events related with mitochondrial respiration, plant development and redox homeostasis. We analyzed single and double homozygous mutants in both CYTc-encoding genes from Arabidopsis: CYTC-1 and CYTC-2. While individual mutants were similar to wild-type, knock-out of both genes produced an arrest of embryo development, showing that CYTc function is essential at early stages of plant development. Mutants in which CYTc levels were extremely reduced respective to wild-type had smaller rosettes with a pronounced decrease in parenchymatic cell size and an overall delay in development. Mitochondria from these mutants had lower respiration rates and a relative increase in alternative respiration. Furthermore, the decrease in CYTc severely affected the activity and the amount of Complex IV, without affecting Complexes I and III. Reactive oxygen species levels were reduced in these mutants, which showed induction of genes encoding antioxidant enzymes. Ascorbic acid levels were not affected, suggesting that a small amount of CYTc is enough to support its normal synthesis. We postulate that, in addition to its role as an electron carrier between Complexes III and IV, CYTc influences Complex IV levels in plants, probably reflecting a role of this protein in Complex IV stability. This double function of CYTc most likely explains why it is essential for plant survival.

O2k-Network Lab: DE Hannover Hildebrandt T

Labels: MiParea: Respiration, Genetic knockout;overexpression 

Stress:Oxidative stress;RONS  Organism: Plants 

Preparation: Intact cells, Isolated mitochondria  Enzyme: Complex I, Complex III, Complex IV;cytochrome c oxidase  Regulation: Cyt c  Coupling state: ROUTINE, OXPHOS  Pathway: S, ROX  HRR: Oxygraph-2k 

Alternative oxidase