Calla B, MacLean M, Liao L-H, Dhanjal I, Tittiger C, Blomquist G J, Berenbaum M R
Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV, USA.
Insect Mol Biol. 2018 Oct;27(5):661-674. doi: 10.1111/imb.12516. Epub 2018 Jul 31.
Determining the functionality of CYP4G11, the only CYP4G in the genome of the western honey bee Apis mellifera, can provide insight into its reduced CYP4 inventory. Toward this objective, CYP4G11 transcripts were quantified, and CYP4G11 was expressed as a fusion protein with housefly CPR in Sf9 cells. Transcript levels varied with age, task, and tissue type in a manner consistent with the need for cuticular hydrocarbon production to prevent desiccation or with comb wax production. Young larvae, with minimal need for desiccation protection, expressed CYP4G11 at very low levels. Higher levels were observed in nurses, and even higher levels in wax producers and foragers, the latter of which risk desiccation upon leaving the hive. Recombinant CYP4G11 readily converted octadecanal to n-heptadecane in a time-dependent manner, demonstrating its functions as an oxidative decarbonylase. CYP4G11 expression levels are high in antennae; heterologously expressed CYP4G11 converted tetradecanal to n-tridecane, demonstrating that it metabolizes shorter-chain aldehydes. Together, these findings confirm the involvement of CYP4G11 in cuticular hydrocarbon production and suggest a possible role in clearing pheromonal and phytochemical compounds from antennae. This possible dual functionality of CYP4G11, i.e., cuticular hydrocarbon and comb wax production and antennal odorant clearance, may explain how honey bees function with a reduced CYP4G inventory.
确定西方蜜蜂（Apis mellifera）基因组中唯一的细胞色素P450 4家族成员11（CYP4G11）的功能，有助于深入了解其细胞色素P450 4（CYP4）数量减少的情况。为实现这一目标，对CYP4G11转录本进行了定量分析，并在昆虫杆状病毒表达系统（Sf9）细胞中将CYP4G11与家蝇细胞色素P450还原酶（CPR）融合表达为融合蛋白。转录水平随年龄、任务和组织类型而变化，这种变化方式与为防止干燥而产生表皮碳氢化合物或与蜂蜡生产的需求一致。对干燥保护需求最小的幼虫，其CYP4G11表达水平极低。在哺育蜂中观察到较高水平，而在泌蜡蜂和采集蜂中水平更高，采集蜂离开蜂巢后有干燥风险。重组CYP4G11能以时间依赖性方式将十八醛迅速转化为正十七烷，证明其作为氧化脱羰酶的功能。CYP4G11在触角中的表达水平较高；异源表达的CYP4G11将十四醛转化为正十三烷，表明它能代谢较短链的醛类。这些发现共同证实了CYP4G11参与表皮碳氢化合物的产生，并提示其在清除触角上的信息素和植物化学物质方面可能发挥作用。CYP4G11这种可能的双重功能，即参与表皮碳氢化合物和蜂蜡的产生以及清除触角上的气味物质，或许可以解释蜜蜂如何在细胞色素P450 4数量减少的情况下发挥功能。
