Yamasaki M, Redenbach M, Kinashi H
Department of Molecular Biotechnology, Hiroshima University, Kagamiyama, Japan.
Mol Gen Genet. 2001 Jan;264(5):634-42. doi: 10.1007/s004380000349.
The linear plasmid SCP1 is integrated into the central region of the chromosome of Streptomyces coelicolor A3(2). The integrated structures of SCP1 in two bidirectional donor strains, 2612 and A634, were analyzed by cloning and sequencing of the junctions between the SCP1 DNA and the chromosomal DNA. In the NF (normal fertility) strain 2612, SCP1 is integrated in a right-handed direction into ORF-X at the left end of the IS cluster in AseI fragment E. An almost intact left end of SCP1 is retained, while the right terminal inverted repeat (TIR-R) of SCP1 and a 33-kb chromosomal DNA segment including the IS cluster are deleted. In the NF-like strain A634, SCPI is also integrated into AseI fragment E in a left-handed direction. The left junction is composed of IS466 with complete deletion of TIR-R of SCP1, and the right junction is located at the left end of IS468A* with half of TIR-L being deleted. During the integration event, a 5.4-kb chromosomal DNA segment including IS468A, IS468B, IS469 and IS466A was duplicated so that this sequence is now present on both sides of SCP1. Since 2612 and A634 exhibit a similar bidirectional gradient of gene transfer, it is surprising that their chromosomal structures are so different.
线性质粒SCP1整合到天蓝色链霉菌A3(2)染色体的中央区域。通过对SCP1 DNA与染色体DNA之间连接点进行克隆和测序，分析了SCP1在两个双向供体菌株2612和A634中的整合结构。在NF（正常育性）菌株2612中，SCP1以右手方向整合到AseI片段E中IS簇左端的ORF-X中。SCP1几乎完整的左端得以保留，而SCP1的右末端反向重复序列（TIR-R）和包括IS簇在内的一个33 kb染色体DNA片段被删除。在类NF菌株A634中，SCP1也以左手方向整合到AseI片段E中。左连接点由IS466组成，SCP1的TIR-R完全缺失，右连接点位于IS468A*的左端，TIR-L的一半被删除。在整合过程中，一个包括IS468A、IS468B、IS469和IS466A的5.4 kb染色体DNA片段发生了重复，因此该序列现在存在于SCP1的两侧。由于2612和A634表现出相似的双向基因转移梯度，令人惊讶的是它们的染色体结构如此不同。
