Research article

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

Thomas Pohl^{* 1} , Julia Walter^{* 1} , Stefan Stolpe¹ , Joel H Defeu Soufo² , Peter L Grauman² and Thorsten Friedrich¹

¹Institute of Organic Chemistry and Biochemistry, University of Freiburg, Albertstrasse 21, 79104 Freiburg, Germany

²Institute of Microbiology, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg, Germany

author email corresponding author email* Contributed equally

BMC Biochemistry 2007, 8:13doi:10.1186/1471-2091-8-13

Published:	24 July 2007

Abstract

Background

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 Thermus thermophilus. It was not clear whether frataxin is in general a component of complex I from bacteria. The Escherichia coli homologue of frataxin is coined CyaY.

Results

We report that complex I is completely assembled to a stable and active enzyme complex equipped with all known iron-sulfur clusters in a cyaY mutant of E. coli. 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.

Conclusion

CyaY plays a non-essential role in the assembly of complex I in E. coli. It is not a structural component but may transiently interact with the complex.