Effects of the deletion of the Escherichia coli frataxin homologue CyaY on the respiratory NADH:ubiquinone oxidoreductase

<p>Abstract</p> <p>Background</p> <p>Frataxin is discussed as involved in the biogenesis of iron-sulfur clusters. Recently it was discovered that a frataxin homologue is a structural component of the respiratory NADH:ubiquinone oxidoreductase (complex I) in <it>Thermus thermophilus</it>. It was not clear whether frataxin is in general a component of complex I from bacteria. The <it>Escherichia coli </it>homologue of frataxin is coined CyaY.</p> <p>Results</p> <p>We report that complex I is completely assembled to a stable and active enzyme complex equipped with all known iron-sulfur clusters in a <it>cyaY </it>mutant of <it>E. coli</it>. However, the amount of complex I is reduced by one third compared to the parental strain. Western blot analysis and live cell imaging of CyaY engineered with a GFP demonstrated that CyaY is located in the cytoplasm and not attached to the membrane as to be expected if it were a component of complex I.</p> <p>Conclusion</p> <p>CyaY plays a non-essential role in the assembly of complex I in <it>E. coli</it>. It is not a structural component but may transiently interact with the complex.</p