胃型LYZ c的主要功能是裂解反刍动物胃中的微生物,释放营养物质,为机体提供养分.为了揭示水牛胃型LYZ c基因的遗传特征,采用PCR产物直接测序技术,对66头河流型和158头沼泽型水牛样品胃型LYZ c基因完整编码区序列进行了变异检测,并结合已发表的牛科物种同源序列进行了比较基因组学和生物信息学分析.在水牛群体内共发现9个SNP位点,分别为c.87G>T、c.196G>A、c.228G>A、c.336G>C、c.351T>C、c.396C>T、c.423C>T、c.424G>A和c.438C>G,其中SNP87、SNP196、SNP336和SNP351仅存在于河流型水牛中,其他5个SNP为河流型和沼泽型水牛共享;SNP196和SNP424为异义替换,引起p.G66S和p.V142I氨基酸替换,但它们对水牛LYZ c的功能没有影响.在水牛胃型LYZ c基因中,共定义7种单倍型,确定了3种LYZ c变异体,其中变异体Buffalo 1、Buffalo 2为两类水牛共享,Buffalo 3为河流型水牛独有.水牛这3种变异体之间在氨基酸组成、理化特性与结构上基本一致.水牛与普通牛胃型LYZ c蛋白的上述特征也极相似,但水牛胃型LYZ c的等电点比普通牛更低.结果揭示水牛胃型LYZ c蛋白可能更适合胃中的酸性环境,具有分解胃中微生物的功能.%The main function of the stomach LYZ c is to break open the microbes in the stomach of ruminants, release their nutrients and provide nutrients for the host body. In order to reveal the genetic characteristics of buffalo stomach LYZ c gene,the variations in the complete coding region of buffalo stomach LYZ c gene were detected in 66 river and 158 swamp buffalo samples by adopting the technique of PCR product direct sequencing. Combined with published homologous sequences of some bovine species,the data in this study were further analysed by the methods of comparative genomics and bioinformatics. A total of 9 SNP sites were found in water buffalo,namely c. 87G>T, c. 196G>A,c. 228G>A,c. 336G>C,c. 351T>C,c. 396C>T,c. 423C>T,c. 424G>A and c. 438C>G,re-spectively. Among them,SNP87,SNP196,SNP336 and SNP351 were only found in river buffalo,and the other 5 SNPs were shared by river and swamp buffalo. The SNP196 and SNP424 were non-synonymous substitution,which result in p. G66S and p. V142I amino acid changes. This two substitutions were presumed to have no effect on the function of buffalo stomach LYZ c. Based on the variations in buffalo stomach LYZ c gene,7 haplotypes were defined from which 3 protein variants were identified. Among them,variant Buffalo 1 and Buffalo 2 were shared by two kinds of water buffalo,and Buffalo 3 was unique to river buffalo. The amino acid compositions,physiochemical properties and structures of the three variants are basically the same. The above characteristics of buffalo stomach LYZ c are very similar to those of cattle,but the isoelectric point of buffalo stomach LYZ c is lower than that of cattle. The re-sults of this study indicate that buffalo stomach LYZ c is more suitable for the acid environment of the stomach,and it has the function of breaking down the microbes in the stomach.
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