Thousands of terpenes have been identified to date. However, only two classes of enzymes are known to be involved in their biosynthesis, and each class has characteristic amino-acid motifs. We recently identified a novel large-terpene (C₂₅/C₃₀/C₃₅) synthase, which shares no motifs with known enzymes. To elucidate the molecular mechanism of this enzyme, we determined the crystal structure of a large-β-prene synthase from B. alcalophilus (BalTS). Surprisingly, the overall structure of BalTS is similar to that of the α-domain of class I terpene synthases although their primary structures are totally different from each other. Two novel aspartate-rich motifs, DYLDNLxD and DY(F,L,W)IDxxED, are identified, and mutations of any one of the aspartates eliminate its enzymatic activity. The present work leads us to propose a new subclass of terpene synthases, class IB, which is probably responsible for large-terpene biosynthesis.

中文翻译：

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晶体结构和属于新发现的子类的大萜类合成酶的功能分析†

迄今已鉴定出数千种萜烯。然而，已知只有两类酶参与其生物合成，并且每一类都具有特征性的氨基酸基序。我们最近发现了一种新型的大萜（C ₂₅ / C ₃₀ / C ₃₅）合酶，它与已知的酶没有任何基序。为了阐明该酶的分子机制，我们确定了嗜碱芽孢杆菌的大β-戊二烯合酶的晶体结构。（BalTS）。出人意料的是，BalTS的整体结构与I类萜烯合酶的α结构域相似，尽管它们的主要结构完全不同。鉴定了两个新颖的富含天冬氨酸的基序，DYLDNLxD和DY（F，L，W）IDxxED，并且任一天冬氨酸的突变消除了其酶促活性。目前的工作使我们提出了一个新的萜类合成酶亚类，即IB类，这可能是大萜生物合成的原因。