4O79

Crystal Structure of Ascorbate-bound Cytochrome b561, crystal soaked in 1 M L-ascorbate for 10 minutes

Summary for 4O79

• Entry DOI: 10.2210/pdb4o79/pdb
• Related: 4O6Y 4O7G
• Descriptor: Probable transmembrane ascorbate ferrireductase 2, PROTOPORPHYRIN IX CONTAINING FE, SULFATE ION, ... (5 entities in total)
• Functional Keywords: alpha helical membrane protein, ascorbate-dependent oxidoreductase, oxidoreductase
• Biological source: Arabidopsis thaliana (thale-cress)
• Cellular location: Membrane; Multi-pass membrane protein (Potential): Q9SWS1
• Total number of polymer chains: 2
• Total formula weight: 53358.34

Authors

Lu, P.,Ma, D.,Yan, C.,Gong, X.,Du, M.,Shi, Y. (deposition date: 2013-12-24, release date: 2014-02-05, Last modification date: 2023-11-08)

Primary citation

Lu, P.,Ma, D.,Yan, C.,Gong, X.,Du, M.,Shi, Y.
Structure and mechanism of a eukaryotic transmembrane ascorbate-dependent oxidoreductase
Proc.Natl.Acad.Sci.USA, 111:1813-1818, 2014

PubMed Abstract: Vitamin C, also known as ascorbate, is required in numerous essential metabolic reactions in eukaryotes. The eukaryotic ascorbate-dependent oxidoreductase cytochrome b561 (Cyt b561), a family of highly conserved transmembrane enzymes, plays an important role in ascorbate recycling and iron absorption. Although Cyt b561 was identified four decades ago, its atomic structure and functional mechanism remain largely unknown. Here, we report the high-resolution crystal structures of cytochrome b561 from Arabidopsis thaliana in both substrate-free and substrate-bound states. Cyt b561 forms a homodimer, with each protomer consisting of six transmembrane helices and two heme groups. The negatively charged substrate ascorbate, or monodehydroascorbate, is enclosed in a positively charged pocket on either side of the membrane. Two highly conserved amino acids, Lys(81) and His(106), play an essential role in substrate recognition and catalysis. Our structural and biochemical analyses allow the proposition of a general electron transfer mechanism for members of the Cyt b561 family.

PubMed: 24449903
DOI: 10.1073/pnas.1323931111

Experimental method

X-RAY DIFFRACTION (2.003 Å)