MOLECULAR CHARACTERIZATION OF THE CLOSTRIDIUM-DIFFICILE TOXIN-A GENE
MOLECULAR CHARACTERIZATION OF THE CLOSTRIDIUM-DIFFICILE TOXIN-A GENE
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DOI：
10.1128/iai.58.2.480-488.1990
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发表时间：
1990-02-01
影响因子：
3.1
通讯作者：
JOHNSON, JL
中科院分区：
文献类型：
--
作者：
DOVE, CH;WANG, SZ;JOHNSON, JL
克隆了编码艰难梭菌（VPI 10463株）毒素A蛋白的基因并进行了序列测定。编码区8,133个碱基，G + C摩尔%为26.9，编码2,710个氨基酸。推导出的多肽分子量约为1000。308千道尔顿。近三分之一的基因，在3“末端，由38个重复序列组成。根据重复单位的长度和它们之间DNA序列相似性的低水平，将它们分为两类，I和II。 有7个I类重复单元，每个单元含有90个核苷酸，和31个II类单元，除了两个例外，长度为60或63个核苷酸。根据DNA序列相似性，将II类重复单元进一步分成亚类：7个IIA类、13个IIB类、5个IIC类和6个IID类。酪氨酸-苯丙氨酸二肽存在于所有38个重复单元中，其他氨基酸序列是特定类别或亚类所特有的。该蛋白质的该区域具有单克隆抗体PCG-4的表位，并包括Gal α 1 - 3Gal β 1 -4GlcNAc碳水化合物受体的结合区域。毒素B基因的3“末端位于毒素A翻译起始位点上游1，350个碱基对处。在两个毒素基因之间是一个小的开放阅读框，它编码ca. 16或19千道尔顿。这种开放式阅读框架的作用尚不清楚。
The gene encoding the toxin A protein of Clostridium difficile (strain VPI 10463) was cloned and sequenced. The coding region of 8,133 base pairs has a mol% G + C of 26.9 and encodes 2,710 amino acids. The deduced polypeptide has a molecular mass of ca. 308 kilodaltons. Nearly a third of the gene, at the 3'' end, consists of 38 repeating sequences. The repeating units were grouped into two classes, I and II, on the basis of length and the low levels of DNA sequence similarities between them. There were seven class I repeating units, each containing 90 nucleotides, and 31 class II units, which, with two exceptions, were either 60 or 63 nucleotides in length. On the basis of DNA sequence similarities, the class II repeating units were further segregated into subclasses: 7 class IIA, 13 class IIB, 5 class IIC, and 6 class IID. The dipeptide tyrosine-phenylalanine was found in all 38 repeating units, and other amino acid sequences were unique to a specific class or subclass. This region of the protein has epitopes for the monoclonal antibody PCG-4 and includes the binding region for the Gal.alpha.1-3Gal.beta.1-4GlcNAc carbohydrate receptor. Located 1,350 base pairs upstream from the toxin A translation start site is the 3'' end of the toxin B gene. Between the two toxin genes is a small open reading frame, which encodes a deduced polypeptide of ca. 16 or 19 kilodaltons. The role of this open reading frame is unknown.