1MXT

Atomic resolution structure of Cholesterol oxidase (Streptomyces sp. SA-COO)

Summary for 1MXT

• Entry DOI: 10.2210/pdb1mxt/pdb
• Related: 1B4V 1B8S 1CBO 1CC2 1IJH
• Descriptor: CHOLESTEROL OXIDASE, SULFATE ION, FLAVIN-N7 PROTONATED-ADENINE DINUCLEOTIDE, ... (5 entities in total)
• Functional Keywords: flavoenzyme, steroid metabolism, oxidoreductase, atomic resolution
• Biological source: Streptomyces sp.
• Cellular location: Secreted: P12676
• Total number of polymer chains: 1
• Total formula weight: 55884.30

Authors

Vrielink, A.,Lario, P.I. (deposition date: 2002-10-03, release date: 2003-02-25, Last modification date: 2023-09-13)

Primary citation

Lario, P.I.,Sampson, N.,Vrielink, A.
Sub-atomic resolution crystal structure of cholesterol oxidase: What atomic resolution crystallography reveals about enzyme mechanism and the role of FAD cofactor in redox activity
J.Mol.Biol., 326:1635-1650, 2003

PubMed Abstract: The crystal structure of cholesterol oxidase, a 56kDa flavoenzyme was anisotropically refined to 0.95A resolution. The final crystallographic R-factor and R(free) value is 11.0% and 13.2%, respectively. The quality of the electron density maps has enabled modeling of alternate conformations for 83 residues in the enzyme, many of which are located in the active site. The additional observed structural features were not apparent in the previous high-resolution structure (1.5A resolution) and have enabled the identification of a narrow tunnel leading directly to the isoalloxazine portion of the FAD prosthetic group. The hydrophobic nature of this narrow tunnel suggests it is the pathway for molecular oxygen to access the isoalloxazine group for the oxidative half reaction. Resolving the alternate conformations in the active site residues provides a model for the dynamics of substrate binding and a potential oxidation triggered gating mechanism involving access to the hydrophobic tunnel. This structure reveals that the NE2 atom of the active site histidine residue, H447, critical to the redox activity of this flavin oxidase, acts as a hydrogen bond donor rather than as hydrogen acceptor. The atomic resolution structure of cholesterol oxidase has revealed the presence of hydrogen atoms, dynamic aspects of the protein and how side-chain conformations are correlated with novel structural features such as the oxygen tunnel. This new structural information has provided us with the opportunity to re-analyze the roles played by specific residues in the mechanism of the enzyme.

PubMed: 12595270
DOI: 10.1016/S0022-2836(03)00054-8

Experimental method

X-RAY DIFFRACTION (0.95 Å)