Dynamic structure of the mitrochondrial cytochrome bc1 complex

S. H. Kim, Z. Zhang, L. S. Huang, Y. I. Chi, K. K. Kim, L. W. Hung, K. A. Bcrry

Research output: Contribution to journalArticlepeer-review

Abstract

We have crystallized complex ill (the < vtochrome bc.i complex) in hexagona.l(P6522) crystals from cow and rabbit. monoclinir(P2] ) crystals from cow. and orthorhornbic(P212121} cry-, t als from chicken. The chicken crystals diffract to 3.0 A. The orthorhoinbic and inonoclinic crystals each have a dimor of the bc'i complex in ilio asymmetric unit. Thii allows us to address questions about the symmetry of t lie dimnc lie, compiex Structural evidence .supports t.lie hypothfMh tliat tlic reaction mechanism involves movement of the Riosko irorisulfur protein bei ween a proximal position, in which t he cluster üganri H 161 hydrogen bonds with, and ato-pis UK electron from, qtiinol at center Q,: and a distal position in which eleci ron transfer wiih cytorhronie CT takes place. Cytochrorne c1 core strmture similar to Ambler's Class L cytochrornes. without the loop corresponding to residues 41-58 in cvtochrome c. I his nx pooses the hene propionaies allowing the cytochrome to be reduced by the Rieskc protein tiironeli this side of the heme. As in oilier Class I cylochromes. the C rorrnof the hemeis exposed. This faces away from the membrane and scnnii likely to be ihe binding s te for cvlnchroine <. Klectron densitv in cocrvstais of the chicken bcj complex wiili hoi> heart cytochrome c support this position for cyochiome however the cytochromee is somewhat disordered in these crystals and the orientation cannto be determined rigorously at the current stage of analysis.

Original languageEnglish (US)
Pages (from-to)A1308
JournalFASEB Journal
Volume12
Issue number8
StatePublished - 1998

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