State Key Laboratory of Rice Biology, Key laboratory of Agricultural Entomology, the Ministry of Agriculture of China, Hangzhou, Zhejiang, China.
Insect Mol Biol. 2013 Aug;22(4):366-75. doi: 10.1111/imb.12028. Epub 2013 Apr 19.
Ceramidases are a group of enzymes that catalyse hydrolysis of ceramides to generate fatty acid and sphingosine. In this study, we report the cloning and characterization of the rice small brown planthopper Laodelphax striatellus neutral ceramidase (nCDase), LsnCer. LsnCer was identified by sequencing the transcriptome of L. striatellus and is a protein of 717 amino acids with a predicted molecular weight of 79.3 kDa. Similarly to other known nCDases, the optimum pH for LsnCer is 8.0 and the optimum temperature is 37 °C for its in vitro activity. LsnCer activity is inhibited by Zn(2+) significantly and Fe(2+) slightly. LsnCer has broad substrate specificity with a preference for ceramides with a medium acyl-chain or a monounsaturated long acyl-chain. Infection with rice strip virus (RSV) or treatment with insecticides significantly increased LsnCer mRNA expression and its enzymatic activity in L. striatellus. These results suggest that LsnCer is a bona fide nCDase that may have a role in adaption of L. striatellus to environmental stresses.
神经酰胺酶是一组能够催化神经酰胺水解生成脂肪酸和神经鞘氨醇的酶。本研究通过测序鉴定了褐飞虱（Laodelphax striatellus）中性神经酰胺酶（nCDase）基因，并对其进行了克隆和功能分析。LsnCer 基因编码一个 717 个氨基酸的蛋白，预测分子量为 79.3 kDa。与其它已报道的 nCDase 相似，LsnCer 的最适 pH 为 8.0，最适反应温度为 37℃。Zn(2+)对 LsnCer 活性有明显的抑制作用，Fe(2+)则有轻微的抑制作用。LsnCer 具有广泛的底物特异性，对中长链酰基神经酰胺或单不饱和长链酰基神经酰胺具有偏好性。感染水稻条纹病毒（RSV）或用杀虫剂处理均能显著增加褐飞虱 LsnCer 的 mRNA 表达和酶活性。这些结果表明 LsnCer 是一种真正的 nCDase，可能在褐飞虱适应环境胁迫中发挥作用。
