Allard J D, Bertrand K P
Department of Microbiology, Washington State University, Pullman 99164.
J Bacteriol. 1993 Jul;175(14):4554-60. doi: 10.1128/jb.175.14.4554-4560.1993.
We determined the nucleotide sequence of the class E tetA gene on plasmid pSL1456 from Escherichia coli SLH1456A. The deduced amino acid sequence of the class E TetA protein shows 50 to 56% identity with the sequences of five related TetA proteins (classes A through D and G). Hydrophobicity profiles identify 12 putative transmembrane segments with similar boundaries in all six TetA sequences. The N-terminal alpha domain of the six sequences is more highly conserved than the C-terminal beta domain; the central hydrophilic loop connecting the alpha and beta domains is the least conserved region. Amino acid residues that have been shown to be important for class B (Tn10) TetA function are conserved in all six TetA sequences. Unlike the class B tetA gene, the class D and E tetA genes do not exhibit a negative gene dosage effect when present on multicopy plasmids derived from pACYC177.
我们测定了来自大肠杆菌SLH1456A的质粒pSL1456上E类tetA基因的核苷酸序列。推导的E类TetA蛋白氨基酸序列与五种相关TetA蛋白（A至D类和G类）的序列具有50%至56%的同一性。疏水性图谱确定了所有六个TetA序列中具有相似边界的12个推定跨膜区段。六个序列的N端α结构域比C端β结构域保守性更高；连接α和β结构域的中央亲水环是保守性最低的区域。已证明对B类（Tn10）TetA功能重要的氨基酸残基在所有六个TetA序列中都是保守的。与B类tetA基因不同，D类和E类tetA基因存在于源自pACYC177的多拷贝质粒上时，不表现出负基因剂量效应。
