蚤状溞(Daphnia pulex)基因组中MDM2/4类似蛋白及其编码基因的特征

摘要

[目的]验证蚤状溞基因组是否存在与人类原癌基因MDM2/4同源或相似的基因,为拓展蚤状溞作为模式生物在生物医学领域中的应用奠定基础.[方法]在GenBank中同源搜索蚤状溞MDM2/4基因及其编码蛋白,利用生物信息学工具软件对其基因结构、转录本序列、编码蛋白的性质和结构等进行生物信息学分析.[结果]用BLASTp程序在GenBank蛋白非冗余数据库中对编码的氨基酸序列进行搜索,获得了蚤状溞基因组编码的MDM2/4类似蛋白,并分别命名为DAPPU mdm2_like和DAPPU_rndm4_like.根据EST序列确定蚤状溞MDM2/4类似基因仅有5个外显子.BLAST比对搜索、亚细胞定位预测、功能结构域分析及同源模建预测结果表明,DAPPU_mdm2_like和DAP-PU_mdm4_like可能是MDM2/4的同源蛋白,DAPPU_mdm2 like的结构功能域含有1个ZnF_RBZ结构域(氨基酸135～159)、1个RING结构域(氨基酸250～290)和RING结构域重叠部分序列形成的另一个ZnF_RBZ结构域(氨基酸269～293)；DAPPU_mdm4_like氨基酸222～263可能是一个RING结构域.利用Needleman-Wunsch双序列全局比对工具比对,发现DAPPU_mdm4_like与DAPPU_mdm2_like具有28.6％的序列一致性和40.4％的相似性.[结论]蚤状潘基因组可能存在MDM2和MDM4的分化.%[Objective]Studying the MDM2/4 albuminoid encoded in the genome of Daphnia pulex will provide references for applying Daphnia pulex to biomedicine field as a model organism.[Method] MDM2/4 albuminoid and coding protein of Daphnia pulex were identified in GenBank to analyze gene structure,transcript sequence,traits and structure of coding protein using bioinformatical software.[Resuh]After searching coding amino acid sequence in non-redundant Gen-Bank by BLASTp application,the putative MDM2/4 proteins encoded in genome of Daphnia pulex were identified and designated as DAPPU_mdm2_like and DAPPU_mdm4_like,respectively.The MDM2/4 genes had only 5 exons according to EST sequence.The results from BLAST querying,prediction of subcellular location,prediction of function/structure domain and homology modeling of the structure showed that they were likely to be the MDM2/4 homologue.The DAPPU_mdm2_like structure function domain contained one ZnF_RBZ domain (amino acid 135-159),one RING domain (amino acid 250-290),and another ZnF_RBZ domain overlapping with RING domain (amino acid 269-293).Amino acid 250-290 in DAPPU_mdm4_like could be a RING domain.Using double and global alignment comparison tool of Needleman-Wunsch,it was found that DAPPU_mdm4_like and DAPPU_mdm2_like shared 28.6％ alignment identities and 40.4％ similarity.[Conclusion]It seemed that Daphnia pulex had the differentiation of MDM2 and MDM4 similar proteins.