4rev
Structure of the dirigent protein DRR206Structure of the dirigent protein DRR206
Structural highlights
FunctionDR206_PEA Dirigent proteins impart stereoselectivity on the phenoxy radical-coupling reaction, yielding optically active lignans from two molecules of coniferyl alcohol in the biosynthesis of lignans, flavonolignans, and alkaloids and thus plays a central role in plant secondary metabolism. Publication Abstract from PubMedControl 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 A resolution, rhombohedral space group H32)) is reported herein. It has a tightly packed trimeric structure with an eight-stranded beta-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. Trimeric Structure of (+)-Pinoresinol-forming Dirigent Protein at 1.95 A Resolution with Three Isolated Active Sites.,Kim KW, Smith CA, Daily MD, Cort JR, Davin LB, Lewis NG J Biol Chem. 2015 Jan 16;290(3):1308-18. doi: 10.1074/jbc.M114.611780. Epub 2014 , Nov 19. PMID:25411250[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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