Catechol 1,2-dioxygenase was first studied by Hayaishi and colleagues in 1950. In 1967, catechol 1,2-dioxygenase from Pseudomonas arvilla C-1 (PaCTD) was chosen as a model system for the catecholic intradiol dioxygenases due to its activity, stability and expression level. Here we report the 2.65 Å structure of the ββ isozyme of PaCTD. The structure supports the hypothesis first made by Vetting and Ohlendorf [The 1.8 Å crystal structure of catechol 1,2-dioxygenase reveals a novel hydrophobic helical zipper as a subunit linker, Struct. Fold. Des. 8 (2000) 429-440.] that the catechol 1,2-dioxygenases are lipid binding proteins. The 5 amino-terminal helices involved in dimerization and forming the lipid binding site are shown to be plastic in their positions and orientations. The sequence differences between the α and β polypeptides are located at the part of the monomers distant from dimerization surface and thus permit the formation of the 3 isozymes (αα, αβ, and ββ) of PaCTD. The reported inactivation by sulfhydryl-modifying reagents is explained by the structure. The 10-residue Helix F (residues 203-212) is proposed to be central in communicating between the lipid binding site and the active site.
|Original language||English (US)|
|Number of pages||8|
|Journal||Biochemical and Biophysical Research Communications|
|State||Published - Dec 9 2005|
Bibliographical noteFunding Information:
This work has been partially supported by grants from the National Institutes of Health (GM-46436 to D.H.O., GM-33162 to L.Q.). The authors would also like to thank Ms. Debi Leverich for technical assistance, Dr. John Lipscomb for helpful discussions, the Minnesota Supercomputer Institute for the use of computational facilities, and Mr. Ed Hoeffner for maintaining the diffraction facilities at the University of Minnesota.
- Intradiol dioxygenase
- Lipid binding protein
- Nonheme iron
- X-ray crystallography