2VNX

Crystal structure of soybean ascorbate peroxidase mutant W41A after exposure to a high dose of x-rays

Summary for 2VNX

• Entry DOI: 10.2210/pdb2vnx/pdb
• Related: 1OAF 1OAG 1V0H 2CL4 2GGN 2GHC 2GHD 2GHE 2GHH 2GHK 2VCF 2VCN 2VCS 2VNZ
• Descriptor: ASCORBATE PEROXIDASE, PROTOPORPHYRIN IX CONTAINING FE, SODIUM ION, ... (4 entities in total)
• Functional Keywords: apx, peroxidase, heme enzyme, oxidoreductase, reduction by x-rays
• Biological source: GLYCINE MAX (SOYBEAN)
• Total number of polymer chains: 1
• Total formula weight: 28886.25

Authors

Metcalfe, C.L.,Badyal, S.K.,Raven, E.L.,Moody, P.C.E. (deposition date: 2008-02-08, release date: 2008-04-08, Last modification date: 2023-12-13)

Primary citation

Badyal, S.K.,Metcalfe, C.L.,Basran, J.,Efimov, I.,Moody, P.C.E.,Raven, E.L.
Iron Oxidation State Modulates Active Site Structure in a Heme Peroxidase.
Biochemistry, 47:4403-, 2008

PubMed Abstract: We have previously shown [Badyal, S. K., et al. (2006) J. Biol. Chem. 281, 24512-24520] that the distal histidine (His42) in the W41A variant of ascorbate peroxidase binds to the heme iron in the ferric form of the protein but that binding of the substrate triggers a conformational change in which His42 dissociates from the heme. In this work, we show that this conformational rearrangement also occurs upon reduction of the heme iron. Thus, we present X-ray crystallographic data to show that reduction of the heme leads to dissociation of His42 from the iron in the ferrous form of W41A; spectroscopic and ligand binding data support this observation. Structural evidence indicates that heme reduction occurs through formation of a reduced, bis-histidine-ligated species that subsequently decays by dissociation of His42 from the heme. Collectively, the data provide clear evidence that conformational movement within the same heme active site can be controlled by both ligand binding and metal oxidation state. These observations are consistent with emerging data on other, more complex regulatory and sensing heme proteins, and the data are discussed in the context of our developing views in this area.

PubMed: 18351739
DOI: 10.1021/BI702337N

Experimental method

X-RAY DIFFRACTION (1.5 Å)