Lack of cytochrome c in Arabidopsis decreases stability of Complex IV and modifies redox metabolism without affecting Complexes i and III

authored by

Elina Welchen, Tatjana M. Hildebrandt, Dagmar Lewejohann, Daniel H. Gonzalez, Hans Peter Braun

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.

Organisation(s)

Institute of Plant Genetics
Section Plant Molecular Biology and Plant Proteomics

External Organisation(s)

Universidad Nacional del Litoral

Type

Article

Journal

Biochimica et Biophysica Acta - Bioenergetics

Volume

1817

Pages

990-1001

No. of pages

12

ISSN

0005-2728

Publication date

18.04.2012

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Biophysics, Biochemistry, Cell Biology

Electronic version(s)

https://doi.org/10.1016/j.bbabio.2012.04.008 (Access: Open)