Trimeric structure of (+)-pinoresinol-forming dirigent protein at 1.95 Å resolution with three isolated active sites.
Trimeric structure of (+)-pinoresinol-forming dirigent protein at 1.95 Å resolution with three isolated active sites.
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DOI：
10.1074/jbc.m114.611780
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发表时间：
2015-01-16
期刊：
影响因子：
--
通讯作者：
Lewis NG
中科院分区：
文献类型：
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作者：
Kim KW;Smith CA;Daily MD;Cort JR;Davin LB;Lewis NG
背景：发散蛋白（DP）的发现为植物中单木质素衍生的偶联提供了新的范例。结果：在1.95 nm处获得了（+）-Pinocyanol-forming DP（PsDRR 206）的三维结构。结论：紧密堆积的三聚体DP有三个假定的底物结合位点，空间上相距很远，这表明每个位点直接涉及单体偶联。重要性：植物中单分子自由基-自由基偶联的新见解。在维管植物体内，对苯氧基自由基-自由基偶联反应的控制一直是个谜，直到我们发现了dirigent蛋白（DP，来自拉丁语dirigere，引导或对齐）。本文报道了DP的第一个三维结构（（+）-形成松醇的DP，1.95 μ m分辨率，菱形空间群H32））。它具有紧密堆积的三聚体结构，每个DP单体具有八链β-桶拓扑结构。每个假定的底物结合和取向偶联位点位于三聚体表面上，但对于位点之间的分子间偶联来说相距太远。有人建议，每个网站使立体选择性耦合（使用两个松柏醇自由基或自由基和monolithyl）。有趣的是，DP中有6个差异保守的残基，在已知控制立体选择性的假定结合位点和区域附近提供（+）-或（-）-对映体。DP参与木酚素生物合成，而dirigent结构域/位点参与木质素沉积。
Background: Dirigent protein (DP) discovery gave new paradigm for monolignol-derived coupling in planta. Results: (+)-Pinoresinol-forming DP (PsDRR206) three-dimensional structure was obtained at 1.95 Å resolution. Conclusion: The tightly packed trimeric DP has three putative substrate binding sites spatially far apart, suggesting that each site involves monomer coupling directly. Significance: New insights into monolignol radical-radical coupling in planta. 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.