State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.
Biological Science Research Center, Southwest University, Chongqing, China.
J Insect Sci. 2020 Nov 1;20(6). doi: 10.1093/jisesa/ieaa132.
Aldehyde oxidases (AOXs) are a subfamily of cytosolic molybdo-flavoenzymes that play critical roles in the detoxification and degradation of chemicals. Active AOXs, such as AOX1 and AOX2, have been identified and functionally analyzed in insect antennae but are rarely reported in other tissues. This is the first study to isolate and characterize the cDNA that encodes aldehyde oxidase 5 (BmAOX5) in the pheromone gland (PG) of the silkworm, Bombyx mori. The size of BmAOX5 cDNA is 3,741 nucleotides and includes an open reading frame, which encodes a protein of 1,246 amino acid residues. The theoretical molecular weight and isoelectric point of BmAOX5 are approximately 138 kDa and 5.58, respectively. BmAOX5 shares a similar primary structure with BmAOX1 and BmAOX2, containing two [2Fe-2S] redox centers, a FAD-binding domain, and a molybdenum cofactor (MoCo)-binding domain. RT-PCR revealed BmAOX5 to be particularly highly expressed in the PG (including ovipositor) of the female silkworm moth, and the expression was further confirmed by in situ hybridization, AOX activity staining, and anti-BmAOX5 western blotting. Further, BmAOX5 was shown to metabolize aromatic aldehydes, such as benzaldehyde, salicylaldehyde, and vanillic aldehyde, and fatty aldehydes, such as heptaldehyde and propionaldehyde. The maximum reaction rate (Vmax) of benzaldehyde as substrate was 21 mU and Km was 1.745 mmol/liter. These results suggested that BmAOX5 in the PG could metabolize aldehydes in the cytoplasm for detoxification or participate in the degradation of aldehyde pheromone substances and odorant compounds to identify mating partners and locate suitable spawning sites.
醛氧化酶（AOXs）是细胞溶质钼黄素酶的一个亚家族，在化学物质的解毒和降解中发挥关键作用。活性 AOX，如 AOX1 和 AOX2，已在昆虫触角中被鉴定和功能分析，但在其他组织中很少报道。这是首次在蚕的香腺中分离和表征醛氧化酶 5（BmAOX5）的 cDNA。BmAOX5 cDNA 的大小为 3741 个核苷酸，包括一个开放阅读框，编码 1246 个氨基酸残基的蛋白质。BmAOX5 的理论分子量和等电点约为 138 kDa 和 5.58。BmAOX5 与 BmAOX1 和 BmAOX2 具有相似的一级结构，包含两个[2Fe-2S]氧化还原中心、一个 FAD 结合域和一个钼辅因子（MoCo）结合域。RT-PCR 显示 BmAOX5 在雌性蚕蛾的香腺（包括产卵器）中表达特别高，通过原位杂交、AOX 活性染色和抗 BmAOX5 免疫印迹进一步证实。此外，BmAOX5 被证明可以代谢芳香醛，如苯甲醛、水杨醛和香草醛，以及脂肪醛，如庚醛和丙醛。苯甲醛作为底物的最大反应速率（Vmax）为 21 mU，Km 为 1.745 mmol/L。这些结果表明，PG 中的 BmAOX5 可以代谢细胞质中的醛以解毒，或参与醛类信息素物质和气味化合物的降解，以识别交配伙伴并找到合适的产卵地点。
