原生动物阴道毛滴虫的酵酶长寿保障基因LAG1同源基因克隆和序列分析

为了探讨寄生性原虫阴道毛滴虫细胞生长和衰老相关基因,作者从阴道毛滴虫的cDNA表达文库中分离出一具910碱基对的cDNA克隆,其编码框长834bp,推测蛋白质序列有277个氨基酸.序列分析显示该克隆与酵酶长寿保障基因LAG1同源性最高,其氨基酸序列中含有LAG1及其同源基因保守的Lag1结构域和TLC结构域以及6个跨膜螺旋区和一个C-未端的内质网保留信号域.因此推测该克隆系酵酶LAG1的同源基因,该基因可能参与阴道毛滴虫的神经酰胺生物合成以及调解细胞的生命期或细胞衰老.该基因的基因组DNA与其cDNA序列一致,提示该基因序列中可能无内含子.

A homolog of the yeast longevity assurance gene LAG1 in the parasitic protist Trichomonas vaginalis

In an effort to search and analyze cell growth and senescence related genes of the parasitic protist Trichomonas vaginalis , we launched an EST program and isolated a cDNA clone with a length of 910 basepairs from a T.vaginalis cDNA library.The sequence analysis revealed that this cDNA clone contains an open reading frame of 834 bp.The deduced amino acid sequence has 277 residues and is most homologous to the longevity assurance gene 1(LAG1)proteins.A predicted Lag1 motif and a TLC domain conserved in Lag1 proteins were detected in the amino acid sequence.The secondary structure analysis demonstrated that this protein possesses six predicted transmembrane domains and a membrane retention signal of endoplasmic reticulum.These data suggest that this clone is probably a LAG1 homolog,which may participate in the regulation of ceramide biosynthesis and in determining life span or cell senescence of the protozoan.The genomic DNA of this gene is also cloned and sequenced.The DNA sequence is identical to that of cDNA,suggesting it may be a intronless gene of the protozoan.