Okinaka R, Cloud K, Hampton O, Hoffmaster A, Hill K, Keim P, Koehler T, Lamke G, Kumano S, Manter D, Martinez Y, Ricke D, Svensson R, Jackson P
Life Sciences Division, Los Alamos National Laboratory, NM 87545, USA.
J Appl Microbiol. 1999 Aug;87(2):261-2. doi: 10.1046/j.1365-2672.1999.00883.x.
Bacillus anthracis plasmids pX01 and pX02, harboured by the Sterne and Pasteur strains, respectively, have been sequenced by random 'shotgun' cloning and high throughout sequence analysis. These sequences have been assembled (Sequencher) to generate a circulate pX01 plasmid containing 181 656 bp and a single linear (gapped) pX02 contig containing at least 93.479 bp. Initial annotation suggests that the two plasmids combined contain at least 200 potential open reading frames (ORFs) with < 40% having significant similarity to sequences registered in open databases. Collectively, only 118 566 bp of the pX01 DNA (65%) represent predicted coding regions. This value is similar to published gene densities for other plasmids and is indicative of the larger intergenic spaces in plasmids vs those found in the chromosomes of the parental microbes (85-93% gene density). A 70 kbp region including the toxin genes (cya, lef and pag) is distinct from the remainder of the pX01 sequence: (1) it has a lower gene density (58 vs 70%) than the remaining 111 kbp; (2) it contains all but one of the co-regulated transcriptional fusions identified by transposon mutagenesis (Hoffmaster & Koehler 1997) and (3) it contains a significantly higher proportion of positive BLAST scores (62 vs 20%) for putative ORFs. These data suggest different origins for the two regions of pX01.
炭疽芽孢杆菌质粒pX01和pX02，分别由斯特恩菌株和巴斯德菌株携带，已通过随机“鸟枪法”克隆和高通量序列分析进行了测序。这些序列已被组装（Sequencher软件），以生成一个包含181656 bp的环状pX01质粒和一个至少包含93479 bp的单一线性（有缺口）pX02重叠群。初步注释表明，这两个质粒总共包含至少200个潜在的开放阅读框（ORF），其中不到40%与公开数据库中登记的序列有显著相似性。总体而言，pX01 DNA中只有118566 bp（65%）代表预测的编码区域。这个值与其他质粒公布的基因密度相似，表明质粒中的基因间隔比亲代微生物染色体中的基因间隔更大（基因密度为85 - 93%）。一个包含毒素基因（cya、lef和pag）的70 kbp区域与pX01序列的其余部分不同：（1）它的基因密度（58%对70%）低于其余111 kbp；（2）它包含了通过转座子诱变鉴定的所有共调控转录融合体，但有一个除外（霍夫马斯特和克勒，1997年）；（3）对于推定的ORF，它包含的阳性BLAST得分比例显著更高（62%对20%）。这些数据表明pX01的两个区域有不同的起源。
