Sequence and organization of pXO1, the large Bacillus anthracis plasmid harboring the anthrax toxin genes
Sequence and organization of pXO1, the large Bacillus anthracis plasmid harboring the anthrax toxin genes
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DOI：
10.1128/jb.181.20.6509-6515.1999
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发表时间：
1999-10-01
影响因子：
3.2
通讯作者：
Jackson, PJ
中科院分区：
文献类型：
--
作者：
Okinaka, RT;Cloud, K;Jackson, PJ
炭疽杆菌Sterne质粒pXO 1通过随机“鸟枪”克隆测序。产生181，654bp的环状序列。使用GeneMark和GeneMark.hmm预测了143个开放阅读框（ORF），仅占pXO 1 DNA序列的61%（110，817 bp）。质粒的总体鸟嘌呤加胞嘧啶含量为32.5%。该质粒最易识别的特征是一个“致病岛”，由一个44.8 kb的区域定义，该区域的两端与反向IS1627元件相邻。该区域包含三个毒素基因（cya、lef和pagA）、控制毒素基因的调控元件、三个发芽反应基因和19个额外的ORF。pXO1上近70%的ORF与开放数据库中的序列没有显著的相似性。pXO1序列中缺少与驱动θ复制和维持芽孢杆菌属中大质粒稳定性所需的基因的同源物。在与已知序列高度相似的ORF中，有一组推定的转座酶、解离酶和整合酶，表明物种间DNA的横向运动涉及进化。在剩余的ORF中，有三个序列可能编码负责合成多糖荚膜的酶，通常与特定型的毒性链球菌有关。
The Bacillus anthracis Sterne plasmid pXO1 was sequenced by random, "shotgun" cloning. A circular sequence of 181,654 bp was generated. One hundred forty-three open reading frames (ORFs) were predicted using GeneMark and GeneMark.hmm, comprising only 61% (110,817 bp) of the pXO1 DNA sequence. The overall guanine-plus-cytosine content of the plasmid is 32.5%. The most recognizable feature of the plasmid is a "pathogenicity island," defined by a 44.8-kb region that is bordered by inverted IS1627 elements at each end. This region contains the three toxin genes (cya, lef, and pagA), regulatory elements controlling the toxin genes, three germination response genes, and 19 additional ORFs. Nearly 70% of the ORFs on pXO1 do not have significant similarity to sequences available in open databases. Absent from the pXO1 sequence are homologs to genes that are typically required to drive theta replication and to maintain stability of large plasmids in Bacillus spp. Among the ORFs with a high degree of similarity to known sequences are a collection of putative transposases, resolvases, and integrases, suggesting an evolution involving lateral movement of DNA among species. Among the remaining ORFs, there are three sequences that may encode enzymes responsible for the synthesis of a polysaccharide capsule usually associated with serotype-specific virulent streptococci.