tailieunhanh - Báo cáo khoa học: Structure of a trypanosomatid mitochondrial cytochrome c with heme attached via only one thioether bond and implications for the substrate recognition requirements of heme lyase

The principal physiological role of mitochondrial cytochromecis electron transfer during oxidative phosphorylation. c-Type cytochromes are almost always characterized by covalent attachment of heme to protein through two thioether bonds between the heme vinyl groups and the thiols of cyste-ine residues in a Cys-Xxx-Xxx-Cys-His motif. | Structure of a trypanosomatid mitochondrial cytochrome c with heme attached via only one thioether bond and implications for the substrate recognition requirements of heme lyase Vilmos Fulop1 Katharine A. Sam2 Stuart J. Ferguson2 Michael L. Ginger3 and James W. A. Allen2 1 Department of BiologicalSciences University of Warwick Coventry UK 2 Department of Biochemistry University of Oxford UK 3 Schoolof Health and Medicine Division of Biomedicaland Life Sciences Lancaster University UK Keywords Cytochrome c heme lyase intermembrane space thioether bond trypanosome Correspondence J. W. A. Allen Department of Biochemistry University of Oxford South Parks Road Oxford OX1 3QU UK Fax 44 0 1865 613201 Tel 44 0 1865 613330 E-mail Database X-ray structure coordinates for Crithidia fasciculata cytochrome c have been deposited in the Protein Data Bank under the accession code 2w9k Received 23 December 2008 revised 19 February 2009 accepted 13 March 2009 doi The principal physiological role of mitochondrial cytochrome c is electron transfer during oxidative phosphorylation. c-Type cytochromes are almost always characterized by covalent attachment of heme to protein through two thioether bonds between the heme vinyl groups and the thiols of cysteine residues in a Cys-Xxx-Xxx-Cys-His motif. Uniquely however members of the evolutionarily divergent protist phylum Euglenozoa which includes Trypanosoma and Leishmania species have mitochondrial cytochromes c with heme attached through only one thioether bond to an AZF XXCH motif the implications of this for the cytochrome structures are unclear. Here we present the A resolution X-ray crystal structure of cytochrome c from the trypanosomatid Crithidia fasciculata. Despite the fundamental difference in heme attachment and in the cytochrome c biogenesis machinery of the Euglenozoa the structure is remarkably similar to that of typical CXXCH mitochondrial cytochromes c both