title: X-ray structure of a truncated form of cytochrome f from chlamydomonas reinhardtii.
abstract: A truncated form of cytochrome f from Chlamydomonas reinhardtii (an important eukaryotic model organism for photosynthetic electron transfer studies) has been crystallized (space group P2(1)2(1)2(1); three molecules/asymmetric unit) and its structure determined to 2.0 A resolution by molecular replacement using the coordinates of a truncated turnip cytochrome f as a model. The structure displays the same folding and detailed features as turnip cytochrome f, including (a) an unusual heme Fe ligation by the alpha-amino group of tyrosine 1, (b) a cluster of lysine residues (proposed docking site of plastocyanin), and (c) the presence of a chain of seven water molecules bound to conserved residues and extending between the heme pocket and K58 and K66 at the lysine cluster. For this array of waters, we propose a structural role. Two cytochrome f molecules are related by a noncrystallographic symmetry operator which is a distorted proper 2-fold rotation. This may represent the dimeric relation of the monomers in situ; however, the heme orientation suggested by this model is not consistent with previous EPR measurements on oriented membranes.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA.
authors.forename: Y I
authors.initials: YI
authors.lastname: Chi
authors.forename: L S
authors.initials: LS
authors.lastname: Huang
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: J G
authors.initials: JG
authors.lastname: Fernández-Velasco
authors.forename: E A
authors.initials: EA
authors.lastname: Berry
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000737:chemistry* / Q000201:enzymology; D018360:Crystallography, X-Ray; D003580:Cytochromes / Q000737:chemistry* / Q000235:genetics; D045348:Cytochromes f; D019281:Dimerization; D006418:Heme / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
chemical_list: D003580:Cytochromes; D006418:Heme; D045348:Cytochromes f; D008239:Lysine