Linked Life Data

10387032

Source:http://linkedlifedata.com/resource/pubmed/id/10387032

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
25
pubmed:dateCreated
1999-7-22
pubmed:abstractText
The cytochrome (cyt) c1 heme of the ubihydroquinone:cytochrome c oxidoreductase (bc1 complex) is covalently attached to two cysteine residues of the cyt c1 polypeptide chain via two thioether bonds, and the fifth and sixth axial ligands of its iron atom are histidine (H) and methionine (M), respectively. The latter residue is M183 in Rhodobacter capsulatus cyt c1, and previous mutagenesis studies revealed its critical role for the physicochemical properties of cyt c1 [Gray, K. A., Davidson, E., and Daldal, F. (1992) Biochemistry 31, 11864-11873]. In the homologous chloroplast b6f complex, the sixth axial ligand is provided by the amino group of the amino terminal tyrosine residue. To further pursue our investigation on the role played by the sixth axial ligand in heme-protein interactions, novel cyt c1 variants with histidine-lysine (K) and histidine-histidine axial coordination were sought. Using a R. capsulatus genetic system, the cyt c1 mutants M183K and M183H were constructed by site-directed mutagenesis, and chromatophore membranes as well as purified bc1 complexes obtained from these mutants were characterized in detail. The studies revealed that these mutants incorporated the heme group into the mature cyt c1 polypeptides, but yielded nonfunctional bc1 complexes with unusual spectroscopic and thermodynamic properties, including shifted optical absorption maxima (lambdamax) and decreased redox midpoint potential values (Em7). The availability and future detailed studies of these stable cyt c1 mutants should contribute to our understanding of how different factors influence the physicochemical and folding properties of membrane-bound c-type cytochromes in general.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
22
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7908-17
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Substitution of the sixth axial ligand of Rhodobacter capsulatus cytochrome c1 heme yields novel cytochrome c1 variants with unusual properties.
pubmed:affiliation
Department of Biology, Plant Science Institute, University of Pennsylvania, Philadelphia 19104, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't