Trimeric structure of (+)-pinoresinol-forming dirigent protein at 1.95 Å resolution with three isolated active sites.
Control over phenoxy radical-radical coupling reactions in vivo in vascular plants was enigmatic until our discovery of dirigent proteins (DPs, from the Latin dirigere, to guide or align). The first three-dimensional structure of a DP ((+)-pinoresinol-forming DP, 1.95 Å resolution, rhombohedral space group H32)) is reported herein. It has a tightly packed trimeric structure with an eight-stranded β-barrel topology for each DP monomer. Each putative substrate binding and orientation coupling site is located on the trimer surface but too far apart for intermolecular coupling between sites. It is proposed that each site enables stereoselective coupling (using either two coniferyl alcohol radicals or a radical and a monolignol). Interestingly, there are six differentially conserved residues in DPs affording either the (+)- or (-)-antipodes in the vicinity of the putative binding site and region known to control stereoselectivity. DPs are involved in lignan biosynthesis, whereas dirigent domains/sites have been implicated in lignin deposition.
['Kim|Kye-Won|KW|', 'Smith|Clyde A|CA|', 'Daily|Michael D|MD|', 'Cort|John R|JR|', 'Davin|Laurence B|LB|', 'Lewis|Norman G|NG|']
D000438:Alcohols D000595:Amino Acid Sequence D020134:Catalytic Domain D003001:Cloning, Molecular D018360:Crystallography, X-Ray D005663:Furans D017705:Lignans D008031:Lignin D062105:Molecular Docking Simulation D008969:Molecular Sequence Data D018532:Peas D010940:Plant Proteins D011485:Protein Binding D055503:Protein Multimerization D017433:Protein Structure, Secondary D013237:Stereoisomerism D013379:Substrate Specificity
Dirigent Proteins Crystallography Homology Modeling Molecular Docking Phenoxy Radical Radical Coupling Protein Crystallization Secondary Metabolism