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Mutants of Methylobacterium extorquens and Paracoccus denitrificans deficient in c-type cytochrome biogenesis synthesise the methylamine-dehydrogenase polypeptides but cannot assemble the tryptophan-tryptophylquinone group.

Authors
  • Page, M D
  • Ferguson, S J
Type
Published Article
Journal
European journal of biochemistry / FEBS
Publication Date
Dec 01, 1993
Volume
218
Issue
2
Pages
711–717
Identifiers
PMID: 8269962
Source
Medline
License
Unknown

Abstract

Five mutants of Methylobacterium extorquens and four mutants of Paracoccus denitrificans that have a general defect in c-type cytochrome synthesis also failed to assemble an active methylamine dehydrogenase. In all cases methanol dehydrogenase, another periplasmic enzyme, was fully active. All nine mutant strains accumulated both the heavy and light subunits of methylamine dehydrogenase to essentially wild-type levels. In all nine mutants, the heavy-subunit and light-subunit polypeptides were proteolytically processed, suggesting that translocation to the periplasm had occurred; in the case of the P. denitrificans mutants, a periplasmic location for the heavy and light subunits was confirmed experimentally. While specific quinone staining of the methylamine dehydrogenase light subunit in wild-type M. extorquens and P. denitrificans strains could readily be demonstrated, the light subunit polypeptides accumulated by the mutants did not quinone stain, indicating that the methylamine dehydrogenase prosthetic group, tryptophan tryptophylquinone, is not assembled in the absence of functional c-type cytochromes.

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