Linear plasmid SLP2 of Streptomyces lividans is a composite replicon
Linear plasmid SLP2 of Streptomyces lividans is a composite replicon
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DOI：
10.1046/j.1365-2958.2003.03403.x
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发表时间：
2003-03-01
影响因子：
3.6
通讯作者：
Chen, CW
中科院分区：
文献类型：
--
作者：
Huang, CH;Chen, CY;Chen, CW
SLP2是lividans链霉菌中的一个50 kb的线性质粒，包含短（44 bp）的末端反向重复序列和共价结合的末端蛋白。测定SLP2的核苷酸序列。最右侧15.4 kb的序列与宿主染色体相同，包括边缘的Tn4811序列，该序列被SLP2中的插入序列（is）元件中断。对Tn4811侧翼靶序列的检查表明在那里有一个先前的重组事件。43个推测的蛋白质编码序列包含许多参与复制（包括两个末端蛋白同源物）、分配、偶联转移和淀粉内扩散的蛋白质编码序列。末端定位的解旋酶样基因ttrA是配偶转移所必需的。这两个端粒在一级序列上有明显的差异，但保留了相似的二级结构。含有这些端粒的迷你线状质粒利用染色体编码的末端蛋白在s.lividans中复制。另外，在左端粒附近存在两个假端粒序列。G+C含量和GC或AT倾斜曲线呈现复杂的分布。这些，加上右臂推断的重组，表明SLP2是通过涉及至少三个复制子的交换而进化的。
SLP2 is a 50 kb linear plasmid in Streptomyces lividans that contains short (44 bp) terminal inverted repeats and covalently bound terminal proteins. The nucleotide sequence of SLP2 was determined. The rightmost 15.4 kb sequence is identical to that of the host chromosome, including the Tn4811 sequence at the border, which is interrupted by an insertion sequence (IS) element in SLP2. Examination of the flanking target sequences of Tn4811 suggests a previous recombinational event there. The 43 putative protein coding sequences contained many involved in replication (including two terminal protein homologues), partitioning, conjugal transfer and intramycelial spread. The terminally located helicase-like gene ttrA was necessary for conjugal transfer. The two telomeres diverge significantly in primary sequence, while preserving similar secondary structures. Mini-linear plasmids containing these telomeres replicated in S. lividans using the chromosomally encoded terminal protein. In addition, two pseudotelomere sequences are present near the left telomere. The G+C content and GC or AT skew profiles exhibit complex distributions. These, plus the inferred recombination at the right arm, indicate that SLP2 has evolved through rounds of exchanges involving at least three replicons.