SOLUTION STRUCTURE OF PHENOL HYDROXYLASE PROTEIN-COMPONENT P2 DETERMINED BY NMR-SPECTROSCOPY

Phenol hydroxylase from Pseudomonas sp. CF600 is a member of a family of binuclear iron-center-containing multicomponent oxygenases, which c atalyzes the conversion of phenol and some of its methyl-substituted d erivatives to catechol. In addition to a reductase component which tra nsfers electrons from NADH, optimal turnover of the hydroxylase requir es P2, a protein containing 90 amino acids which is readily resolved f rom the other components. The three-dimensional solution structure of P2 has been solved by 3D heteronuclear NMR spectroscopy. On the basis of 1206 experimental constraints, including 1060 distance constraints obtained from NOEs, 70 phi dihedral angle constraints, 42 psi dihedral angle constraints, and 34 hydrogen bond constraints, a total of 12 co nverged structures were obtained. The atomic root mean square deviatio n for the 12 converged structures with respect to the mean coordinates is 2.48 Angstrom for the backbone atoms and 3.85 Angstrom for all the heavy atoms. This relatively large uncertainty can be ascribed to con formational flexibility and exchange. The molecular structure of P2 is composed of three helices, six antiparallel beta-strands, one beta-ha irpin, and some less ordered regions. This is the first structure amon g the known multicomponent oxygenases. On the basis of the three-dimen sional structure of P2, sequence comparisons with similar proteins fro m other multicomponent oxygenases suggested that all of these proteins may have a conserved structure in the core regions.