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Site-directed modifications indicate differences in axial haem c iron ligation between the related NrfH and NapC families of multihaem c-type cytochromes.

Gross, R. and Eichler, R. and Simon, J. (2005):
Site-directed modifications indicate differences in axial haem c iron ligation between the related NrfH and NapC families of multihaem c-type cytochromes.
In: The Biochemical journal, pp. 689-93, 390, (Pt 3), ISSN 1470-8728,
[Article]

Abstract

During the last decade, a number of related bacterial membrane-bound multihaem c-type cytochromes, collectively referred to as the NapC/NirT family, were identified. These proteins are generally thought to catalyse electron transport between the quinone/quinol pool and periplasmic oxidoreductases. The best-characterized members, the tetrahaem c-type cytochromes NrfH and NapC, mediate electron transport to NrfA and NapA respectively. Amino acid sequence alignments suggest that the nature and position of distal haem c iron ligands differs in NrfH and NapC proteins. Site-directed modification of potential haem c iron-ligating histidine, lysine and methionine residues in Wolinella succinogenes NrfH was performed to determine the implication in electron transport from formate to nitrite. Two histidine, one lysine and one methionine residues were found to be essential, whereas the replacement of three other conserved histidine residues, one methionine and two lysines did not prevent growth by nitrite respiration. The results contrast those previously obtained for Paracoccus pantotrophus NapC, in which four essential histidine residues have been identified that are highly likely to serve as distal haem c iron ligands. The combined experimental evidence suggests different haem ligation patterns within NapC and NrfH proteins, which might reflect their different functions in the bacterial electron transfer.

Item Type: Article
Erschienen: 2005
Creators: Gross, R. and Eichler, R. and Simon, J.
Title: Site-directed modifications indicate differences in axial haem c iron ligation between the related NrfH and NapC families of multihaem c-type cytochromes.
Language: English
Abstract:

During the last decade, a number of related bacterial membrane-bound multihaem c-type cytochromes, collectively referred to as the NapC/NirT family, were identified. These proteins are generally thought to catalyse electron transport between the quinone/quinol pool and periplasmic oxidoreductases. The best-characterized members, the tetrahaem c-type cytochromes NrfH and NapC, mediate electron transport to NrfA and NapA respectively. Amino acid sequence alignments suggest that the nature and position of distal haem c iron ligands differs in NrfH and NapC proteins. Site-directed modification of potential haem c iron-ligating histidine, lysine and methionine residues in Wolinella succinogenes NrfH was performed to determine the implication in electron transport from formate to nitrite. Two histidine, one lysine and one methionine residues were found to be essential, whereas the replacement of three other conserved histidine residues, one methionine and two lysines did not prevent growth by nitrite respiration. The results contrast those previously obtained for Paracoccus pantotrophus NapC, in which four essential histidine residues have been identified that are highly likely to serve as distal haem c iron ligands. The combined experimental evidence suggests different haem ligation patterns within NapC and NrfH proteins, which might reflect their different functions in the bacterial electron transfer.

Journal or Publication Title: The Biochemical journal
Volume: 390
Number: Pt 3
Divisions: 10 Department of Biology > Microbial Energy Conversion and Biotechnology
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10 Department of Biology
Date Deposited: 07 Dec 2010 15:12
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