Zheng Libing, Wu Biao, Liu Zhihong, Tian Jiteng, Yu Tao, Zhou Liqing, Sun Xiujun, Yang Aiguo
Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, Shandong, PR China; College of Fisheries and Life Science, Shanghai Ocean University, 999 Huchenghuan Road, Pudong New District, Shanghai 201306, PR China.
Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, 106 Nanjing Road, Qingdao 266071, Shandong, PR China.
Fish Shellfish Immunol. 2015 Aug;45(2):656-65. doi: 10.1016/j.fsi.2015.05.003. Epub 2015 May 15.
Manganese superoxide dismutase (MnSOD) is one of the key members of the antioxidant defense enzyme family, however, data regarding to the immune function of MnSOD in mollusks still remain limited now. In this study, a full-length MnSOD cDNA was identified by rapid amplification of cDNA ends (RACE) method from cDNA library of ark shell Scapharca broughtonii (termed SbMnSOD). The cDNA contained an open reading frame (ORF) of 696 bp which encoded a polypeptide of 232 amino acids, a 5'-UTR with length of 32 bp and a 3'-UTR of 275 bp. Four putative amino acid residues (His-57, His-105, Asp-190 and His-194) responsible for manganese coordination were located in the most highly conserved regions of SbMnSOD and the signature sequence (DVWEHAYY) also existed in SbMnSOD. The deduced amino acid sequence of SbMnSOD shared high homology to MnSOD from other species. All those data revealed that the SbMnSOD was a novel member of the MnSOD family. The mRNA expression profiles of SbMnSOD in tissues of foot, gill, mantle, adductor muscle, hemocytes and hepatopancreas analyzed by quantitative real-time PCR (qRT-PCR) suggested the mRNA transcripts of SbMnSOD distributed in all the examined tissues. Importantly, Vibrio anguillarum challenge resulted in the increased expression of SbMnSOD mRNA with a regular change trend in all examined tissues, indicating SbMnSOD actively participated in the immune response process. What's more, further analysis on the antibacterial activity of the recombinant SbMnSOD showed that the fusion protein could remarkably inhibit growth of both Gram-positive and Gram-negative bacteria. The present results clearly suggested that SbMnSOD was an acute phase protein involved in the immune reaction in S. broughtonii.
锰超氧化物歧化酶（MnSOD）是抗氧化防御酶家族的关键成员之一，然而，目前关于MnSOD在软体动物免疫功能方面的数据仍然有限。在本研究中，通过cDNA末端快速扩增（RACE）方法从魁蚶（Scapharca broughtonii）的cDNA文库中鉴定出一个全长MnSOD cDNA（命名为SbMnSOD）。该cDNA包含一个696 bp的开放阅读框（ORF），编码一个232个氨基酸的多肽，一个长度为32 bp的5'-非翻译区和一个275 bp的3'-非翻译区。四个负责锰配位的推定氨基酸残基（His-57、His-105、Asp-190和His-194）位于SbMnSOD的高度保守区域，并且特征序列（DVWEHAYY）也存在于SbMnSOD中。SbMnSOD推导的氨基酸序列与其他物种的MnSOD具有高度同源性。所有这些数据表明，SbMnSOD是MnSOD家族的一个新成员。通过定量实时PCR（qRT-PCR）分析SbMnSOD在足、鳃、外套膜、闭壳肌、血细胞和肝胰腺组织中的mRNA表达谱，结果表明SbMnSOD的mRNA转录本分布于所有检测组织中。重要的是，鳗弧菌攻击导致所有检测组织中SbMnSOD mRNA表达增加且呈规律变化趋势，表明SbMnSOD积极参与免疫反应过程。此外，对重组SbMnSOD抗菌活性的进一步分析表明，融合蛋白能够显著抑制革兰氏阳性菌和革兰氏阴性菌的生长。目前的结果清楚地表明，SbMnSOD是参与魁蚶免疫反应的一种急性期蛋白。
