The correlation between the protein composition of cytoplasmic membranes and the formation of nitrate reductase A, chlorate reductase C and tetrathionate reductase inProteus mirabiliswild type and some chlorate resistant mutants
✍ Scribed by L. F. Oltmann; W. N. M. Reijnders; A. H. Stouthamer
- Publisher
- Springer
- Year
- 1976
- Tongue
- English
- Weight
- 674 KB
- Volume
- 111
- Category
- Article
- ISSN
- 0302-8933
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✦ Synopsis
Three genotypically different chlorate resistant mutants, chl I, chl H and chl III, appeared to lack completely nitrate reductase A, chlorate reductase C and tetrathionate reductase activity. Eumarate reductase is only partially affected in chl I and chl III and unaffected in chl II. Formate dehydrogenase is only partially diminished in chllIi hydrogenase is diminished in chl I and chl H and completely absent in chl III.
Subunits of nitrate reductase A, ch]orate reductase C and tetrathionate reductase have been identified in protein profiles of purified cytoplasmic membranes from the wild type and the three mutant strains, grown under various conditions. Only the presence and absence of the largest subunits of these enzymes appeared to be correlated with their repression and derepression in the wild type membranes. On the cytoplasmic membranes of the chl I and chl Ill mutants these subunits lack for the greater part. In the chl H mutant, however, these subunits are inserted in the membrane all together after anaerobic growth with or without nitrate.
A model for the repression/derepression mechanism for the reductases has been proposed. It includes repression by cytochromeb components, whereas the redox-state of the nitrate reductase A molecule itself is also involved in its derepression under anaerobic conditions.