作　　者： ; ; ; ;

机构地区： 华南师范大学生命科学学院

出　　处： 《昆虫学报》 2011年第4期457-466,共10页

摘　　要： 在昆虫中,胆固醇不仅是细胞膜的重要成分之一,也是昆虫蜕皮激素生物合成的前体。由于昆虫体内缺少两种合成胆固醇所必需的关键性酶,所以昆虫不能自主地从简单的前体化合物从头合成胆固醇,而必须通过吸收食物中的甾醇转化为胆固醇来满足生长、发育和繁殖的需要。胆固醇在组织和细胞内的运输主要由固醇转运蛋白(sterolcarrier proteins,SCPs)执行。因此,对固醇转运蛋白结构与功能的研究对于阐明昆虫中固醇运输具有重要的意义。本文对固醇转运蛋白的基因和蛋白结构、细胞内表达和定位、翻译后修饰、蛋白三维结构、底物特异性和可能的运输途径等方面的研究进展进行了综述,并对其作为害虫防治分子靶标的可能性进行了初步的讨论。研究发现,不同物种的SCP蛋白的基因编码形式和蛋白剪切形式不同;双翅目昆虫埃及伊蚊Aedes aegypti和黑腹果蝇Drosophilamelanogaster除了SCP-x基因可编码SCP-x和SCP-2蛋白外,还有另外的SCP-2和类SCP-2(SCP-2L)基因编码SCP-2和类SCP-2蛋白;而鳞翅目昆虫棉贪夜蛾Spodoptera littoralis、斜纹夜蛾Spodoptera litura和家蚕Bombyxmori中SCP-x基因的表达和转录方式与脊椎动物的SCP-x基因类似,通过转录和翻译后剪切形成SCP-2蛋白。SCP-x和SCP-2蛋白定位于过氧化物酶体。SCP-2蛋白由5个α-螺旋和5个β-折叠组成,其中α5-螺旋可影响蛋白与底物的结合。SCP-2蛋白以不同的亲和力与固醇、胆固醇衍生物、脂肪酸、脂酰辅酶A和磷脂等化合物结合。超表达斜纹夜蛾SlSCP-x和SlSCP-2基因可增加细胞对胆固醇的吸收;而利用RNAi技术抑制幼虫体内SlSCP-x表达,可导致血淋巴中的胆固醇含量降低,并导致幼虫生长缓慢,蜕皮化蛹延迟。 In insects,cholesterol is not only one of the main components of cell membranes,but also a precursor of ecdysone biosynthesis. However,because insects lack two key enzymes for cholesterol biosynthesis,they can not autonomously synthesize cholesterol from simple compounds and therefore have to obtain sterols from their diet. Insects must convert food sterols into cholesterol to meet the requirements of growth,development and reproduction. Sterol carrier proteins （SCPs） are main transport proteins for sterol absorption and transport in insects. It is critical to study the relationship between structure and function of SCPs for understanding the roles of SCPs in sterol transport. In this review,recent progress in the study of the structure,expression and distribution of SCP genes and proteins,post-translation modification,crystal structure,ligand-binding specificity and possible absorption and transport pathways of insect SCPs was summarized and the potential of using SCPs as a molecular target for pest insect control was also discussed. Studies indicate that transcript expression of SCP genes and post-translation modifications of SCP proteins vary depending on different species. In dipteran insects such as Aedes aegypti and Drosophila melangoster SCP-x gene encodes SCP-x and SCP-2 proteins,while there are additional SCP-2 genes and SCP-2-like genes encoding SCP-2 and SCP-2-like proteins,respectively. In lepidopteran insects such as Spodoptera littoralis,Spodoptera litura and Bombyx mori,the transcript expression and translation processes of SCP-x gene are similar to those in vertebrates,in which SCP-2 protein is produced after post transcription and translation modifications of a unique SCP-x gene. SCP-x and SCP-2 proteins are localized in peroxisomes. SCP-2 protein consists of 5 α-helixes and 5 β-sheets and the α5-helix appears to impact the binding of the protein to substrates. SCP-2 protein can bind with different affinity to cholesterol,cholesterol derivatives,fatty acids,acyl-coenzyme A and phospholipid

关 键 词： 昆虫 固醇转运蛋白 胆固醇 脂肪酸 蜕皮激素

领　　域： [生物学]