Journal ArticleDOI
The general mitochondrial processing peptidase from wheat is integrated into the cytochrome bc1-complex of the respiratory chain
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TLDR
The composition of the wheat bc1-complex sheds new light on the co-evolution of the processing peptidase and the middle segment of the respiratory chain as shown in an in-vitro processing assay.Abstract:
The bc
1-complex (EC 1.10.2.2.) from Triticum aestivum L. was purified by cytochrome-c affinity chromatography and gel filtration using either etiolated seedlings or wheat-germ extract as starting material. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the isolated enzyme revealed ten bands, which were analysed by immunoblotting and direct amino-acid sequencing. The enzyme from wheat is the first bc
1-complex that is reported to contain four core proteins (55.5, 55.0, 51.5 and 51.0 kDa). In addition, the wheat bc
1-complex comprises cytochrome b (35 kDa), cytochrome c
1 (33 kDa) the “Rieske” iron-sulphur protein (25 kDa) and three small subunits < 15 kDa. This composition differs from the one reported in fungi, mammals and potato. Partial sequence determination of the large subunits suggests that the 55.5 and 55.0-kDa-proteins represent the β-subunit of the general mitochondrial processing peptidase, and the 51.5 and 51.0-kDa proteins the α-subunit of this enzyme. The bc
1-complex from wheat efficiently processes mitochondrial precursor proteins as shown in an in-vitro processing assay. In control experiments the isolated bc
1-complexes from potato, yeast, Neurospora and beef, all purified by the same isolation procedure, were also tested for processing activity. Only the protein complexes from plants contain the general mitochondrial processing peptidase. The composition of the wheat bc
1-complex sheds new light on the co-evolution of the processing peptidase and the middle segment of the respiratory chain.read more
Citations
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Protein import into mitochondria.
TL;DR: Molecular chaperones in the matrix exert multiple functions in translocation, sorting, folding, and assembly of newly imported proteins.
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Structure and Function of Cytochrome bc Complexes
TL;DR: The cytochrome bc complexes represent a phylogenetically diverse group of complexes of electron-transferring membrane proteins, most familiarly represented by the mitochondrial and bacterial bc1 complexes and the chloroplast and cyanobacterial b6f complex.
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Mitochondrial processing peptidases.
TL;DR: Three peptidases are responsible for the proteolytic processing of both nuclearly and mitochondrially encoded precursor polypeptides targeted to the various subcompartments of the mitochondria, and their human homologues begin to be recognized as potential players in mitochondrial disease.
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Atomic structures of respiratory complex III2, complex IV, and supercomplex III2-IV from vascular plants.
TL;DR: Maldonado et al. as mentioned in this paper used a technique called cryo electron microscopy to study the structure of complex III and IV and the supercomplex they formed in the mung bean.
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Mitochondrial protein import in plants. Signals, sorting, targeting, processing and regulation.
TL;DR: The present knowledge on components and mechanisms involved in the mitochondrial protein import process in plants, including properties of targeting peptides, sorting of precursor proteins between mitochondria and chloroplasts, signal recognition, mechanism of translocation across the mitochondrial membranes and the role of cytosolic and organellar molecular chaperones are reviewed.
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