Thiolases are important enzymes involved in lipid metabolism in both prokaryotes and eukaryotes, and are essential for a range of metabolic pathways, while, little is known for this important family in insects. To shed light on the evolutionary models and functional diversities of the thiolase family, 137 thiolase genes were identified in 20 representative insect genomes. They were mainly classified into five classes, namely cytosolic thiolase (CT-thiolase), T1-thiolase, T2-thiolase, trifunctional enzyme thiolase (TFE-thiolase), and sterol carrier protein 2 thiolase (SCP2-thiolase). The intron number and exon/intron structures of the thiolase genes reserve large diversification. Subcellular localization prediction indicated that all the thiolase proteins were mitochondrial, cytosolic, or peroxisomal enzymes. Four highly conserved sequence fingerprints were found in the insect thiolase proteins, including CxS-, NEAF-, GHP-, and CxGGGxG-motifs. Homology modeling indicated that insect thiolases share similar 3D structures with mammals, fishes, and microorganisms. In Bombyx mori, microarray data and reverse transcription-polymerase chain reaction (RT-PCR) analysis suggested that some thiolases might be involved in steroid metabolism, juvenile hormone (JH), and sex pheromone biosynthesis pathways. In general, sequence and structural characteristics were relatively conserved among insects, bacteria and vertebrates, while different classes of thiolases might have differentiation in specific functions and physiological processes. These results will provide an important foundation for future functional validation of insect thiolases.

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昆虫硫解酶家族的全基因组鉴定与分析

硫解酶是参与原核生物和真核生物脂质代谢的重要酶，对一系列代谢途径至关重要，而昆虫中这一重要家族的研究鲜为人知。为了阐明硫解酶家族的进化模型和功能多样性，在 20 个代表性昆虫基因组中鉴定了 137 个硫解酶基因。它们主要分为五类，即胞质硫解酶（CT-硫解酶）、T1-硫解酶、T2-硫解酶、三功能酶硫解酶（TFE-硫解酶）和甾醇载体蛋白2硫解酶（SCP2-硫解酶）。硫解酶基因的内含子数和外显子/内含子结构保留了很大的多样化。亚细胞定位预测表明所有硫解酶蛋白都是线粒体酶、胞质酶或过氧化物酶体酶。在昆虫硫解酶蛋白中发现了四个高度保守的序列指纹，包括 CxS-、NEAF-、GHP-和 CxGGGxG-基序。同源性建模表明昆虫硫解酶与哺乳动物、鱼类和微生物具有相似的 3D 结构。在家蚕中，微阵列数据和逆转录聚合酶链反应 (RT-PCR) 分析表明，一些硫解酶可能参与类固醇代谢、保幼激素 (JH) 和性信息素生物合成途径。总的来说，昆虫、细菌和脊椎动物的序列和结构特征相对保守，而不同类别的硫解酶在特定的功能和生理过程中可能存在差异。这些结果将为未来昆虫硫解酶的功能验证提供重要基础。