2D2C

Crystal Structure Of Cytochrome B6F Complex with DBMIB From M. Laminosus

Summary for 2D2C

• Entry DOI: 10.2210/pdb2d2c/pdb
• Related: 1Q90 1VF5 2E74 2E75 2E76 2ZT9 4H0L 4H13 4H44 4I7Z 4ICJ 4OGQ
• Descriptor: Cytochrome b6, HEME C, (7R,17E)-4-HYDROXY-N,N,N,7-TETRAMETHYL-7-[(8E)-OCTADEC-8-ENOYLOXY]-10-OXO-3,5,9-TRIOXA-4-PHOSPHAHEPTACOS-17-EN-1-AMINIUM 4-OXIDE, ... (16 entities in total)
• Functional Keywords: photosynthesis
• Biological source: Mastigocladus laminosus; More
• Cellular location: Cellular thylakoid membrane; Multi-pass membrane protein: P83791 P83792; Cellular thylakoid membrane; Single-pass membrane protein: P83793 P83795 P83796 P83797 P83798; Cellular thylakoid membrane; Single-pass membrane protein (By similarity): P83794
• Total number of polymer chains: 16
• Total formula weight: 227253.85

Authors

Yan, J.,Kurisu, G.,Cramer, W.A. (deposition date: 2005-09-07, release date: 2005-12-13, Last modification date: 2024-10-23)

Primary citation

Yan, J.,Kurisu, G.,Cramer, W.A.
Intraprotein transfer of the quinone analogue inhibitor 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone in the cytochrome b6f complex
Proc.Natl.Acad.Sci.USA, 103:69-74, 2006

PubMed Abstract: Details are presented of the structural analysis of the cytochrome b(6)f complex from the thermophilic cyanobacterium, Mastigocladus laminosus, in the presence of the electrochemically positive (p)-side quinone analogue inhibitor, 2,5-dibromo-3-methyl-6-isopropylbenzoquinone (DBMIB). One DBMIB binding site was found. This site is peripheral to the quinone binding space defined by the binding sites of other p-side inhibitors previously resolved in cytochrome bc(1)/b(6)f complexes. This high-affinity site resides in a p-side interfacial niche bounded by cytochrome f, subunit IV, and cytochrome b(6), is close (8 A) to the p-side heme b, but distant (19 A) from the [2Fe-2S] cluster. No significant electron density associated with the DBMIB was found elsewhere in the structure. However, the site at which DBMIB can inhibit light-induced redox turnover is within a few A of the [2Fe-2S] cluster, as shown by the absence of inhibition in mutants of Synechococcus sp. PCC 7002 at iron sulfur protein-Leu-111 near the cluster. The ability of a minimum amount of initially oxidized DBMIB to inhibit turnover of WT complex after a second light flash implies that there is a light-activated movement of DBMIB from the distal peripheral site to an inhibitory site proximal to the [2Fe-2S] cluster. Together with the necessary passage of quinone/quinol through the small Q(p) portal in the complex, it is seen that transmembrane traffic of quinone-like molecules through the core of cytochrome bc complexes can be labyrinthine.

PubMed: 16371475
DOI: 10.1073/pnas.0504909102

Experimental method

X-RAY DIFFRACTION (3.8 Å)