Müller Boje, Niephaus Eva, Eisenreich Wolfgang, Bröker Jan Niklas, Twyman Richard M, Prüfer Dirk, Schulze Gronover Christian
Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Johann-Krane-Weg 42, 48149, Münster, Germany.
Structural Membrane Biochemistry, Bavarian NMR Center (BNMRZ), Technical University of Munich (TUM), Lichtenbergstr. 4, 85747, Garching, Germany.
Plant J. 2025 Feb;121(3):e17233. doi: 10.1111/tpj.17233.
The cis-prenyltransferase (cisPT) enzyme family is involved in diverse biological processes that require the synthesis of linear isoprenoid compounds. Taraxacum koksaghyz is a rubber-producing species and potential crop that has eight cisPT homologs (TkCPT1-8) but their distribution and functions are unclear. We compared the structural organization and sequence homology of the proteins, and defined two groups: TkCPT and TkCPT-like (TkCPTL) proteins that form heteromeric cisPT enzymes (TkCPT1-4), and TkCPT proteins that function as homomeric cisPTs (TkCPT5-8). We found that TkCPT1 and TkCPT2 are predominantly expressed in latex whereas TkCPT3 and TkCPT6-8 are predominantly expressed in leaves. TkCPT4 was constitutively expressed in all T. koksaghyz tissues and TkCPT5 mRNA was detected in flowers. The TkCPT1-4 subunits localized to the endoplasmic reticulum whereas TkCPT5-7 were located in chloroplasts. TkCPT1-4 interacted with TkCPTL1-2, forming heteromeric complexes that complemented yeast lacking cisPT. Homomeric TkCPT6 could also complement yeast lacking cisPT but we observed no cisPT activity for TkCPT5, TkCPT7, or TkCPT8 in yeast functional complementation assays. TkCPT1/TkCPTL1 and TkCPT2/TkCPTL1 expressed in yeast produced extra-long-chain polyisoprenes, whereas TkCPT3/TkCPTL1 and TkCPT4/TkCPTL1 produced long-chain dolichols and polyisoprenes, TkCPT5 and TkCPT6 produced medium-chain polyisoprenes, and TkCPT7 and TkCPT8 catalyzed the formation of nerol. The complexity of cisPT proteins in T. koksaghyz suggests that they synthesize different metabolites in a tissue-specific manner, and thus play distinct roles in isoprenoid metabolism. This is the first comprehensive analysis of the localization, interactions, and products of the entire T. koksaghyz cisPT family in vivo, also revealing a novel pentaprenol found specifically in flowers.
顺式异戊烯基转移酶（cisPT）酶家族参与多种需要合成线性类异戊二烯化合物的生物过程。橡胶草是一种产橡胶的物种和潜在作物，有八个cisPT同源物（TkCPT1 - 8），但其分布和功能尚不清楚。我们比较了这些蛋白质的结构组织和序列同源性，并定义了两组：形成异源cisPT酶的TkCPT和TkCPT样（TkCPTL）蛋白（TkCPT1 - 4），以及作为同源cisPT发挥作用的TkCPT蛋白（TkCPT5 - 8）。我们发现TkCPT1和TkCPT2主要在乳胶中表达，而TkCPT3和TkCPT6 - 8主要在叶片中表达。TkCPT4在橡胶草的所有组织中组成性表达，并且在花中检测到TkCPT5 mRNA。TkCPT1 - 4亚基定位于内质网，而TkCPT5 - 7位于叶绿体中。TkCPT1 - 4与TkCPTL1 - 2相互作用，形成补充缺乏cisPT的酵母的异源复合物。同源的TkCPT6也可以补充缺乏cisPT的酵母，但在酵母功能互补试验中，我们未观察到TkCPT5、TkCPT7或TkCPT8的cisPT活性。在酵母中表达的TkCPT1/TkCPTL1和TkCPT2/TkCPTL1产生超长链聚异戊二烯，而TkCPT3/TkCPTL1和TkCPT4/TkCPTL1产生长链多萜醇和聚异戊二烯，TkCPT5和TkCPT6产生中链聚异戊二烯，并且TkCPT7和TkCPT8催化橙花醇的形成。橡胶草中cisPT蛋白的复杂性表明它们以组织特异性方式合成不同的代谢物，因此在类异戊二烯代谢中发挥不同的作用。这是对橡胶草整个cisPT家族在体内的定位、相互作用和产物的首次全面分析，还揭示了一种专门在花中发现的新型戊烯醇。
