CHARACTERIZATION OF A GIARDIA-LAMBLIA VARIANT-SPECIFIC SURFACE PROTEIN (VSP) GENE FROM ISOLATE GS/M AND ESTIMATION OF THE VSP GENE REPERTOIRE SIZE
CHARACTERIZATION OF A GIARDIA-LAMBLIA VARIANT-SPECIFIC SURFACE PROTEIN (VSP) GENE FROM ISOLATE GS/M AND ESTIMATION OF THE VSP GENE REPERTOIRE SIZE
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DOI：
10.1016/0166-6851(92)90072-r
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发表时间：
1992-04-01
影响因子：
1.5
通讯作者：
MOWATT, MR
中科院分区：
文献类型：
--
作者：
NASH, TE;MOWATT, MR
蓝氏贾第鞭毛虫经历表面抗原变异。分离株WB的变异型特异性表面蛋白(VSP)富含半胱氨酸，大小变化很大，含有Cys-X-X-Cys基序，并且存在差异表达。GS/M(H7)是来自不同分离株的贾第鞭毛虫克隆，表达WB中没有的VSP表位。编码该表位的VSP基因是利用来自H7的放射性标记的cDNA和来自表达其他VSP的同一分离株的不同兄弟滋养体品系的差异杂交来选择的。VSPH7基因探针检测到在H7中丰富的1800核苷酸转录本，但在变异的兄弟姐妹中检测不到。直接从RNA中扩增出一条基因序列，预测了一个相对分子质量为56832的蛋白质。该蛋白具有先前测序的2个WB VSP的许多特征，包括许多Cys-X-X-Cys四肽和一个保守的羧基末端区域。基因组Southern分析表明，H7中存在2个不同的VSPH7基因。来自保守区的寡核苷酸与VSPH7基因的特异性寡核苷酸结合使用，估计VSP谱带的大小在133到151之间。VSP，即使是来自表达独特表位的分离物，也构成了一个相关蛋白质家族。
Giardia lamblia undergoes surface antigenic variation. The variant-specific surface proteins (VSPs) of isolate WB are cysteine-rich, can vary dramatically in size, contain Cys-X-X-Cys motifs, and are differentially expressed. GS/M(H7) is a Giardia clone from a different isolate which expresses a VSP epitope not found in WB. The VSP gene encoding this epitope was selected by differential hybridization using radiolabeled cDNA from H7 and variant sibling trophozoite lines from the same isolate that express other VSPs. The VSPH7 gene probe detects an 1800 nucleotide transcript abundant in H7 but undetectable in variant siblings. Primer extension directly from RNA was used to complete the gene sequence which predicted a protein with a molecular weight of 56 832. The protein showed many of the characteristics of 2 previously sequenced WB VSPs including many Cys-X-X-Cys tetrapeptides and a conserved carboxy-terminal region. Genomic Southern analysis indicated the presence of 2 distinct VSPH7 genes in H7. An oligonucleotide from the conserved region was used in combination with one specific for the VSPH7 gene to estimate the VSP repertoire size at between 133 and 151. VSPs, even from isolates expressing unique epitopes, constitute a family of related proteins.