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Affinity purification of yeast cytochrome oxidase with biotinylated subunits 4, 5, or 6
1Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Abstract:
Null mutants in COX4, COX5a, or COX6, which encode subunits 4, 5, and 6 of yeast cytochrome oxidase are blocked in assembly of the enzyme. The mutants are complemented by gene constructs expressing cytochrome oxidase subunits with a carboxyl terminal extension containing a biotinylation signal sequence. Spectra and enzyme activities of mitochondria from transformants expressing a biotinylated subunit indicate restoration of a functional cytochrome oxidase. Biotinylated cytochrome oxidase can be affinity-purified from mitochondrial extracts by fractionation on a monomeric avidin column. This method can be used to purify the enzyme from small amounts of starting material.
Insights
Yeast cytochrome oxidase assembly can be restored using biotinylated subunits. This method enables affinity purification of the enzyme from small mitochondrial samples.
Area of Science:
- Biochemistry
- Molecular Biology
- Yeast Genetics
Background:
- Cytochrome oxidase (COX) is crucial for cellular respiration.
- Assembly of COX requires multiple subunits, and defects can impair function.
- Specific subunits like COX4, COX5a, and COX6 are essential for yeast COX assembly.
Purpose of the Study:
- To investigate methods for restoring functional yeast cytochrome oxidase assembly.
- To develop a novel strategy for purifying cytochrome oxidase using affinity chromatography.
Main Methods:
- Generating null mutants for COX4, COX5a, and COX6 in yeast.
- Complementation of mutants using gene constructs encoding biotinylated cytochrome oxidase subunits.
- Analysis of mitochondrial spectra and enzyme activity.
- Affinity purification using a monomeric avidin column.
Main Results:
- Null mutants were blocked in cytochrome oxidase assembly.
- Expression of biotinylated subunits restored functional cytochrome oxidase.
- Purification of biotinylated cytochrome oxidase from mitochondrial extracts was achieved via avidin affinity chromatography.
Conclusions:
- Biotinylation of cytochrome oxidase subunits can rescue assembly defects.
- Affinity purification using biotinylated cytochrome oxidase is an effective method for enzyme isolation.
- This technique allows for purification from limited starting material.