ISSN:
1573-6881
Keywords:
Mitochondrial processing peptidase MPP
;
bc 1 complex
;
protein import
;
plant mitochondria
;
cytochromec reductase
;
protein processing
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Physics
Notes:
Abstract The mitochondrial general processing peptidase (MPP) in plant mitochondria constitutes an integral part of the cytochromebc 1 complex of the respiratory chain. Here we present a characterization of this bifunctional complex from spinach leaf mitochondria. The purified MPP/bc 1 complex has a molecular mass of 550 kDa, which corresponds to a dimer. Increased ionic strength results in partial dissociation of the dimer as well as loss of the processing activity. Micellar concentrations of nonionic and zwitterionic detergents stimulate the activity by decreasing the temperature optimum of the processing reaction, whereas anionic detergents totally suppress the activity. MPP is a metalloendopeptidase. Interestingly, hemin, a potent regulator of mitochondrial and cytosolic biogenesis and inhibitor of proteosomal degradation, inhibits the processing activity. Measurements of the processing activity at different redox states of thebc 1 complex show that despite bifunctionality of the MPP/bc 1 complex, there is no correlation between electron transfer and protein processing.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02110702
Permalink
