Cytochrome c Reductase from Potato Does not Comprise Three Core Proteins but Contains an Additional Low‐Molecular‐Mass Subunit

authored by: Lothar Jänsch, Volker Kruft, Udo Schmitz, Hans‐Peter Braun
Abstract: Analysis of cytochrome c reductase from potato by Tricine/SDS/PAGE reveals 10 bands representing 10 different subunits. In comparison to glycine/SDS/PAGE one additional small protein becomes visible, whereas the three large core proteins are not resolved. The identity of the subunits was determined by immunoblotting and direct sequence determination. Sequence data for the novel small component were used to derive oligonuleotides for probing a potato cDNA‐library and isolating corresponding clones. The newly identified subunit is a 6.7‐kDa protein, that exhibits significant sequence similatity to a 8.5‐kDa subunit of cytochrome c reductase from yeast and the 6.5‐kDa iron‐sulfur‐protein‐binding factor from the equivalent enzyme complex from beef. Also the potato 6.7‐kDa subunit can be dissociated from the cytochrome c reductase complex together with the iron‐sulfur protein. To address the question of whether three or two core subunits occur simultaneously in monomeric cytochrome c reductase complexes from potato, a peptide‐specific antibody was generated. The antiserum is capable of discriminating between the 55‐kDa and 53‐kDa core proteins, which can be separated by glycine/SDS/PAGE and which were previously found to be structurally related. Immunoprecipitations of isolated cytochrome c reductase from potato using this antibody revealed an enzyme complex containing only two core proteins. The simultaneous occurrence of only two core subunits was confirmed by a comparison of the molecular masses of cytochrome c reductase from potato and beef by blue‐native‐gel electrophoresis. Hence the cytochrome c reductase complexes from potato, beef and yeast have a very conserved subunit composition. The evolutionary implications of these findings are discussed.
External Organisation(s): Applied Biosystems GmbH
Max Planck Institute of Molecular Plant Physiology (MPI-MP)
Type: Article
Journal: European Journal of Biochemistry
Volume: 228
Pages: 878-885
No. of pages: 8
ISSN: 0014-2956
Publication date: 03.1995
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Biochemistry
Electronic version(s): https://doi.org/10.1111/j.1432-1033.1995.tb20335.x (Access: Unknown)

BibTeX

@article{2987bcfab1e643ea9a5cac714b389a60,
title = "Cytochrome c Reductase from Potato Does not Comprise Three Core Proteins but Contains an Additional Low‐Molecular‐Mass Subunit",
abstract = "Analysis of cytochrome c reductase from potato by Tricine/SDS/PAGE reveals 10 bands representing 10 different subunits. In comparison to glycine/SDS/PAGE one additional small protein becomes visible, whereas the three large core proteins are not resolved. The identity of the subunits was determined by immunoblotting and direct sequence determination. Sequence data for the novel small component were used to derive oligonuleotides for probing a potato cDNA‐library and isolating corresponding clones. The newly identified subunit is a 6.7‐kDa protein, that exhibits significant sequence similatity to a 8.5‐kDa subunit of cytochrome c reductase from yeast and the 6.5‐kDa iron‐sulfur‐protein‐binding factor from the equivalent enzyme complex from beef. Also the potato 6.7‐kDa subunit can be dissociated from the cytochrome c reductase complex together with the iron‐sulfur protein. To address the question of whether three or two core subunits occur simultaneously in monomeric cytochrome c reductase complexes from potato, a peptide‐specific antibody was generated. The antiserum is capable of discriminating between the 55‐kDa and 53‐kDa core proteins, which can be separated by glycine/SDS/PAGE and which were previously found to be structurally related. Immunoprecipitations of isolated cytochrome c reductase from potato using this antibody revealed an enzyme complex containing only two core proteins. The simultaneous occurrence of only two core subunits was confirmed by a comparison of the molecular masses of cytochrome c reductase from potato and beef by blue‐native‐gel electrophoresis. Hence the cytochrome c reductase complexes from potato, beef and yeast have a very conserved subunit composition. The evolutionary implications of these findings are discussed.",
keywords = "Cytochrome c reductase, mitochondrial processing peptidase, mitochondrial protein import, respiration, Solanum tuberosum",
author = "Lothar J{\"a}nsch and Volker Kruft and Udo Schmitz and Hans‐Peter Braun",
year = "1995",
month = mar,
doi = "10.1111/j.1432-1033.1995.tb20335.x",
language = "English",
volume = "228",
pages = "878--885",
journal = "European Journal of Biochemistry",
issn = "0014-2956",
publisher = "Wiley-Blackwell Publishing Ltd",
number = "3",
}