Carbonic Anhydrase Subunits Form a Matrix-exposed Domain Attached to the Membrane Arm of Mitochondrial Complex I in Plants

authored by: Stephanie Sunderhaus, Natalya V. Dudkina, Lothar Jänsch, Jennifer Klodmann, Jesco Heinemeyer, Mariano Perales, Eduardo Zabaleta, Egbert J. Boekema, Hans Peter Braun
Abstract: Complex I of Arabidopsis includes five structurally related subunits representing γ-type carbonic anhydrases termed CA1, CA2, CA3, CAL1, and CAL2. The position of these subunits within complex I was investigated. Direct analysis of isolated subcomplexes of complex I by liquid chromatography linked to tandem mass spectrometry allowed the assignment of the CA subunits to the membrane arm of complex I. Carbonate extraction experiments revealed that CA2 is an integral membrane protein that is protected upon protease treatment of isolated mitoplasts, indicating a location on the matrix-exposed side of the complex. A structural characterization by single particle electron microscopy of complex I from the green alga Polytomella and a previous analysis from Arabidopsis indicate a plant-specific spherical extra-domain of about 60 Å in diameter, which is attached to the central part of the membrane arm of complex I on its matrix face. This spherical domain is proposed to contain a heterotrimer of three CA subunits, which are anchored with their C termini to the hydrophobic arm of complex I. Functional implications of the complex I-integrated CA subunits are discussed.
Organisation(s): Section Plant Molecular Biology and Plant Proteomics
Institute of Plant Genetics
External Organisation(s): University of Groningen
Helmholtz Centre for Infection Research (HZI)
Universidad Nacional de Mar del Plata
Type: Article
Journal: Journal of Biological Chemistry
Volume: 281
Pages: 6482-6488
No. of pages: 7
ISSN: 0021-9258
Publication date: 04.01.2006
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Biochemistry, Molecular Biology, Cell Biology
Electronic version(s): https://doi.org/10.1074/jbc.M511542200 (Access: Open)
https://www.jbc.org/content/281/10/6482.full.pdf (Access: Unknown)
https://doi.org/10.15488/11693 (Access: Open)