Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA.
DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, USA.
Plant J. 2024 Nov;120(3):984-997. doi: 10.1111/tpj.17031. Epub 2024 Sep 14.
The Lamiaceae (mint family) is the largest known source of furanoclerodanes, a subset of clerodane diterpenoids with broad bioactivities including insect antifeedant properties. The Ajugoideae subfamily, in particular, accumulates significant numbers of structurally related furanoclerodanes. The biosynthetic capacity for formation of these diterpenoids is retained across most Lamiaceae subfamilies, including the early-diverging Callicarpoideae which forms a sister clade to the rest of Lamiaceae. VacCYP76BK1, a cytochrome P450 monooxygenase from Vitex agnus-castus, was previously found to catalyze the formation of the proposed precursor to furan and lactone-containing labdane diterpenoids. Through transcriptome-guided pathway exploration, we identified orthologs of VacCYP76BK1 in Ajuga reptans and Callicarpa americana. Functional characterization demonstrated that both could catalyze the oxidative cyclization of clerodane backbones to yield a furan ring. Subsequent investigation revealed a total of 10 CYP76BK1 orthologs across six Lamiaceae subfamilies. Through analysis of available chromosome-scale genomes, we identified four CYP76BK1 members as syntelogs within a conserved syntenic block across divergent subfamilies. This suggests an evolutionary lineage that predates the speciation of the Lamiaceae. Functional characterization of the CYP76BK1 orthologs affirmed conservation of function, as all catalyzed furan ring formation. Additionally, some orthologs yielded two novel lactone ring moieties. The presence of the CYP76BK1 orthologs across Lamiaceae subfamilies closely overlaps with the distribution of reported furanoclerodanes. Together, the activities and distribution of the CYP76BK1 orthologs identified here support their central role in furanoclerodane biosynthesis within the Lamiaceae family. Our findings lay the groundwork for biotechnological applications to harness the economic potential of this promising class of compounds.
唇形科（薄荷科）是呋喃型 clerodanes 的最大已知来源，呋喃型 clerodanes 是 clerodane 二萜类的一个亚类，具有广泛的生物活性，包括昆虫拒食特性。Ajugoideae 亚科，特别是，积累了大量结构相关的呋喃型 clerodanes。这些二萜类化合物的生物合成能力保留在大多数唇形科亚科中，包括早期分化的 Callicarpoideae，它与唇形科的其余部分形成姐妹分支。来自 Vitex agnus-castus 的细胞色素 P450 单加氧酶 VacCYP76BK1 之前被发现能够催化呋喃和内酯型 labdane 二萜前体的形成。通过转录组指导的途径探索，我们在 Ajuga reptans 和 Callicarpa americana 中鉴定出 VacCYP76BK1 的同源物。功能表征表明，两者都能够催化 clerodane 骨架的氧化环化，生成呋喃环。随后的研究在六个唇形科亚科中共发现了 10 个 CYP76BK1 同源物。通过对现有染色体规模基因组的分析，我们在不同的亚科中发现了一个保守的共线性块内的四个 CYP76BK1 成员作为 syntelogs。这表明存在一个进化谱系，早于唇形科的物种形成。CYP76BK1 同源物的功能表征证实了功能的保守性，因为所有同源物都催化呋喃环的形成。此外，一些同源物还产生了两个新的内酯环部分。CYP76BK1 同源物在唇形科亚科中的存在与报道的呋喃型 clerodanes 的分布密切重叠。总之，这里鉴定的 CYP76BK1 同源物的活性和分布支持它们在唇形科家族中呋喃型 clerodanes 生物合成中的核心作用。我们的研究结果为利用这一有前途的化合物类别的经济潜力的生物技术应用奠定了基础。
