Internal lipid architecture of the hetero-oligomeric cytochrome b6f complex.

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TitleInternal lipid architecture of the hetero-oligomeric cytochrome b6f complex.
Publication TypeJournal Article
Year of Publication2014
AuthorsS Hasan, S, Cramer, WA
Date Published2014 Jul 08
KeywordsBacterial Proteins, Binding Sites, Crystallography, X-Ray, Cytochrome b6f Complex, Electron Transport, Iron-Sulfur Proteins, Light-Harvesting Protein Complexes, Macromolecular Substances, Membrane Lipids, Membrane Proteins, Models, Molecular, Nostoc, Photosystem I Protein Complex, Protein Kinases, Protein Multimerization, Protein Structure, Quaternary, Protein Structure, Tertiary, Protein Subunits

The role of lipids in the assembly, structure, and function of hetero-oligomeric membrane protein complexes is poorly understood. The dimeric photosynthetic cytochrome b6f complex, a 16-mer of eight distinct subunits and 26 transmembrane helices, catalyzes transmembrane proton-coupled electron transfer for energy storage. Using a 2.5 Å crystal structure of the dimeric complex, we identified 23 distinct lipid-binding sites per monomer. Annular lipids are proposed to provide a connection for super-complex formation with the photosystem-I reaction center and the LHCII kinase enzyme for transmembrane signaling. Internal lipids mediate crosslinking to stabilize the domain-swapped iron-sulfur protein subunit, dielectric heterogeneity within intermonomer and intramonomer electron transfer pathways, and dimer stabilization through lipid-mediated intermonomer interactions. This study provides a complete structure analysis of lipid-mediated functions in a multi-subunit membrane protein complex and reveals lipid sites at positions essential for assembly and function.

Alternate JournalStructure
PubMed ID24931468
PubMed Central IDPMC4105968
Grant ListR01 GM038323 / GM / NIGMS NIH HHS / United States
R56 GM038323 / GM / NIGMS NIH HHS / United States
GM-038323 / GM / NIGMS NIH HHS / United States