三角帆蚌类丝状基质蛋白基因silkmaxin的克隆及其在贝壳和珍珠生物矿化中的作用  

The role of Hyriopsis cumingii shell silk-like matrix protein gene silkmaxin in the shell and pearl biosmineralization

作　　者：夏中慧 刘晓军 李家乐[1,2,3] XIA Zhonghui;LIU Xiaojun;LI Jiale(Key Laboratory of Freshwater Aquatic Genetic Resources,Shanghai Ocean University,Ministry of Agriculture and Rural Affairs,Shanghai 201306,China;National Demonstration Center for Experimental Fisheries Science Education,Shanghai Ocean University,Shanghai 201306,China;Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources,Ministry of Education,Shanghai Ocean University,Shanghai 201306,China)

机构地区：[1]上海洋大学农业农村部淡水种质资源重点实验室,上海201306 [2]上海洋大学水产科学国家级实验教学示范中心,上海201306 [3]上海洋大学,水产种质资源发掘与利用教育部重点实验室,上海201306

出　　处：《水产学报》2019年第12期2449-2458,共10页Journal of Fisheries of China

基　　金：国家自然科学基金(31672654);现代农业产业技术体系建设专项资金(CARS-49);国家科技支撑计划(2012BAD26B04)~~

摘　　要：贝壳基质蛋白指导了珍珠形成过程中碳酸钙的成核、晶体生长和晶型选择等关键 过程。为进一步研究珍珠形成的分子机理,本实验使用RACE-PCR技术克隆得到一个新 的贝壳基质蛋白基因,并命名为silkmaxin。组织表达分析和原位杂交分析表明,该蛋白 于外套膜缘膜部外上表皮组织特异性表达,证明silkmaxin基因所编码的蛋白属于珍珠层 基质蛋白。silkmaxin基质蛋白氨基酸序列富含甘氨酸(Gly,33.0%)和丝氨酸(Ser, 10.4%),蛋白结构由β-折叠构成,类似丝状蛋白结构。分析珍珠形成早期珍珠囊中该蛋 白基因的表达发现,silkmaxin基因在珍珠囊内碳酸钙沉积物从无序到有序的转变过程中 起了重要作用。通过RNA干扰实验可知,贝壳基质蛋白是珍珠层文石小片正常生长不可 缺少的因子,当silkmaxin基因表达被抑制,文石小片的成核、大小和形状均发生了改变。Shell matrix proteins control the nuleation, size and crystal phase of calcium carbonate during the biomineralization of pearl, and they are related to pearl quality. In order to study more about the molecular mechanism of nacre formation, we cloned a novel shell matrix protein silkmaxin (accession No. MK188932) from freshwater mussel Hyriopsis cumingii. With the gene expression detected by RT-PCR and in situ hybridization, silkmaxin was specially expressed in the pallial epithelial cells of mantle outer fold, which indicated that silkmaxin is a nacreous layer matrix protein. The amino acid sequence of silkmaxin featured high proportion of Gly (33.0%) and Ser (10.4%) residues, and the second structure is mainly composed of β-folds. The high structure prediction indicated that silkmaxin is a silk-like protein. In addition, the expression of silkmaxin was detected in the early stage of pearl formation by real-time quantitative PCR. The results indicated that silkmaxin played important roles in the transition of the calcium carbonate disordered deposition to ordered deposition in the early stage of pearl formation. The study of shell by silkmaxin RNAi treatment indicates that silkmaxin gene is essential for the correct growth of aragonite tablets, including the size and shape of the newly formed calcium carbonate crystals.

关 键 词：三角帆蚌 生物矿化 贝壳基质蛋白 类丝状蛋白 珍珠 

分 类 号：Q785[生物学—分子生物学] S966.22+1[农业科学—水产养殖]