DUPLICATION AND VARIATION OF THE THERMOSTABLE DIRECT HEMOLYSIN (TDH) GENE IN VIBRIO-PARAHAEMOLYTICUS
DUPLICATION AND VARIATION OF THE THERMOSTABLE DIRECT HEMOLYSIN (TDH) GENE IN VIBRIO-PARAHAEMOLYTICUS
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DOI：
10.1111/j.1365-2958.1990.tb02017.x
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发表时间：
1990-01-01
影响因子：
3.6
通讯作者：
KAPER, JB
中科院分区：
文献类型：
--
作者：
NISHIBUCHI, M;KAPER, JB
研究了副溶血性弧菌耐热直接溶血素(TdH)基因的表型变异与核苷酸序列变异的关系。具有典型溶血素阳性表型的菌株携带两个染色体基因拷贝(命名为tdh1和tdh2)，而具有弱阳性或阴性溶血素表型的tdh基因阳性菌株仅携带一个染色体基因拷贝。从一株典型的溶血素阳性菌株克隆了两个基因拷贝，并进行了测序，同源性为97.2%。将核苷酸序列预测的氨基酸序列与Edman Degrading测定的蛋白质序列进行比较，构建了一株tdh1缺失的副溶血弧菌，结果表明tdh2基因座是造成副溶血弧菌溶血表型的主要原因。另外两个tdh基因拷贝是从一个表型阴性的菌株中克隆出来的，这是不同寻常的，因为它除了含有染色体上的一个拷贝(Tdh3)外，还在一个质粒上含有一个基因拷贝(命名为tdh4)。在大肠杆菌中表达了ted3和tdh4，并产生了具有溶血活性的tdhs。对这些基因拷贝进行测序，与tdh1基因的同源性为96.7%。携带tdh3和tdh4基因拷贝的副溶血弧菌株不能产生可检测到的tdh特异性RNA转录本。因此，似乎转录调控的差异是溶血表型差异的主要原因。
The relationship between phenotypic variation and nucleotide sequence variation of the gene encoding Vibrio parahaemolyticus thermostable direct haemolysin (tdh gene) was examined. Strains showeing a typical haemolysin-positive phenotype carried two chromosomal gene copies (designated tdh1 and tdh2) whild tdh-gene-positive strains showing a weakly positive or negative haemolysin phenotype possessed only a single chromosomal gene copy. Both gene copies from a typical haemolysin-positive strain were cloned and sequenced n dpossessed 97.2% homology. Comparison of the amino acid sequence predicted from the nucleotide sequence with the protein sequence determined by Edman degraduation as ell as construction of a tdh1-deficient yet haemolytic strain of V. parahaemolyticus suggest that the tdh2 locus is primarily responsible for the heamoloytic phenotype. Two other tdh gene copies were cloned from a phenotypically negative straifn which was unusual in that it contained one gene copy on a plasmid (designated tdh4) in addition to a single copy on the chromosome (tdh3). Both ted3 and tdh4 were expressed in Escherichia coli and TDHs with haemolytic activity were produced. These gene copies were sequenced and shared 96.7% homology with the tdh1 gene. The V. parahaemolyticus strain carrying tdh3 and tdh4 gene copies did not produce detectable amounts of tdh-specific RNA transcript. It seems, therefore, that differences in the transcriptional control are primarily responsible for the differences seen in haemolytic phenotype.