Heme binding constricts the conformational dynamics of the cytochrome b(559)' heme binding cavity.
Cytochrome b(559)' is a transmembrane protein formed by homodimerization of the 44-residue PsbF polypeptide and noncovalent binding of a heme cofactor. The PsbF polypeptide can dimerize in the absence and presence of heme. To monitor structural alterations associated with binding of heme to the apo-cytochrome, we analyzed the apo- and holo-cytochrome structure by electron paramagnetic resonance spectroscopy. Spin labeling of amino acids located close to the heme binding domain of the cytochrome revealed that the structure of the heme binding domain is unconstrained in the absence of heme. Heme binding restricts the conformational dynamics of the heme binding domain, resulting in the structurally more constricted holo-cytochrome structure.
Institut für Pharmazie und Biochemie, Johannes Gutenberg-Universität Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany.
Yasar
Y
Akdogan
Veerappan
V
Anbazhagan
Dariush
D
Hinderberger
Dirk
D
Schneider
D000595:Amino Acid Sequence; D001051:Apoenzymes / Q000737:chemistry / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003573:Cytochrome b Group / Q000737:chemistry* / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D006021:Glycophorins / Q000737:chemistry; D006418:Heme / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013113:Spin Labels; D013696:Temperature
D001051:Apoenzymes; D003573:Cytochrome b Group; D006021:Glycophorins; D010455:Peptides; D045332:Photosystem II Protein Complex; D013113:Spin Labels; D006418:Heme; C019313:cytochrome b559