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The binding domain on horse cytochrome c and Rhodobacter sphaeroides cytochrome c2 for the Rhodobacter sphaeroides cytochrome bc1 complex.
Abstract: The interaction of the Rhodobacter sphaeroides cytochrome bc1 complex with Rb. sphaeroides cytochrome c2 and horse cytochrome c was studied by using specific lysine modification and ionic strength dependence methods. The rate of the reactions with both cytochrome c and cytochrome c2 decreased rapidly with increasing ionic strength above 0.2 M NaCl. The ionic strength dependence suggested that electrostatic interactions were equally important to the reactions of the two cytochromes, even though they have opposite net charges at pH 7.0. In order to define the interaction domain on horse cytochrome c, the reaction rates of derivatives modified at single lysine amino groups with trifluoroacetyl or trifluoromethylphenylcarbamoyl were measured. Modification of lysine-8, -13, -27, -72, -79, and -87 surrounding the heme crevice was found to significantly lower the rate of the reaction, while modification of lysines in other regions had no effect. This result indicates that lysines surrounding the heme crevice of horse cytochrome c are involved in electrostatic interactions with carboxylate groups at the binding site on the cytochrome bc1 complex. In order to define the reaction domain on cytochrome c2, a fraction consisting of a mixture of singly labeled 4-carboxy-2,6-dinitrophenylcytochrome c2 derivatives modified at lysine-35, -88, -95, -97, and -105 and several unidentified lysines was prepared. Although it was not possible to resolve these derivatives, all of the identified lysines are located on the front surface of cytochrome c2 near the heme crevice. The rate of reaction of this fraction was significantly smaller than that of native cytochrome c2, suggesting that the binding domain on cytochrome c2 is also located at the heme crevice.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication Date: 1987-07-14 PubMed ID: 2822095DOI: 10.1021/bi00388a049Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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This research investigates how the Rhodobacter sphaeroides cytochrome bc1 complex interacts with Rb. sphaeroides cytochrome c2 and horse cytochrome c, focusing on the effects of lysine modification and ionic strength. Results reveal that the reactions depend on electrostatic interactions and the heme crevices of these cytochromes.
Interaction Study
- The research set out to study the interaction between the Rhodobacter sphaeroides cytochrome bc1 complex and both cytochrome c2 and horse cytochrome c.
- They employed specific lysine modification methods and observed the effects of varying ionic strengths on this interaction.
- Observations revealed that the rates of reactions with both cytochrome c and cytochrome c2 dropped fast with ionic strength above 0.2 M NaCl.
Role of Electrostatic Interactions
- The study found that electrostatic interactions play equal roles in the reactions of these two cytochromes.
- This was intriguing as the two cytochromes have opposing net charges at pH 7.0, implying that these complex protein interactions do not depend exclusively on charge alignment.
Lysine Modification and its Effects
- To better understand how the horse cytochrome c interacts with the Rb. sphaeroides cytochrome bc1 complex, the researchers experimented with different lysine modifications.
- They discovered that modifications on certain lysine amino groups located around the heme crevice significantly decelerated the reaction rate.
- This tells us that these lysines play a role in the electrostatic interactions with carboxylate groups at the binding site of the cytochrome bc1 complex.
Defining the Reaction Domain on Cytochrome c2
- The researchers also looked at cytochrome c2 and created a fraction consisting of various labeled cytochrome c2 derivatives.
- These derivatives had been modified on several lysines located on the front surface of cytochrome c2 near the heme crevice.
- The modified fraction had a significantly slower reaction rate than the native cytochrome c2.
- This suggests that the binding domain on cytochrome c2 is also located at the heme crevice.
Cite This Article
APA
Hall J, Zha XH, Yu L, Yu CA, Millett F.
(1987).
The binding domain on horse cytochrome c and Rhodobacter sphaeroides cytochrome c2 for the Rhodobacter sphaeroides cytochrome bc1 complex.
Biochemistry, 26(14), 4501-4504.
https://doi.org/10.1021/bi00388a049 Publication
Researcher Affiliations
- Department of Chemistry and Biochemistry, University Arkansas, Fayetteville 72701.
MeSH Terms
- Animals
- Binding Sites
- Cytochrome c Group / metabolism
- Cytochromes c2
- Electron Transport Complex III / metabolism
- Horses
- Kinetics
- Lysine
- Osmolar Concentration
- Protein Binding
- Rhodobacter sphaeroides / metabolism
Grant Funding
- GM20488 / NIGMS NIH HHS
- RR07101 / NCRR NIH HHS
Citations
This article has been cited 3 times.- Janzon J, Yuan Q, Malatesta F, Hellwig P, Ludwig B, Durham B, Millett F. Probing the Paracoccus denitrificans cytochrome c(1)-cytochrome c(552) interaction by mutagenesis and fast kinetics. Biochemistry 2008 Dec 9;47(49):12974-84.
- Sarewicz M, Borek A, Daldal F, Froncisz W, Osyczka A. Demonstration of short-lived complexes of cytochrome c with cytochrome bc1 by EPR spectroscopy: implications for the mechanism of interprotein electron transfer. J Biol Chem 2008 Sep 5;283(36):24826-36.
- Brandner JP, Stabb EV, Temme R, Donohue TJ. Regions of Rhodobacter sphaeroides cytochrome c2 required for export, heme attachment, and function. J Bacteriol 1991 Jul;173(13):3958-65.
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