Evolutionary stability of DNA uptake signal sequences in the Pasteurellaceae
Evolutionary stability of DNA uptake signal sequences in the Pasteurellaceae
复制标题
巴斯德菌科 DNA 摄取信号序列的进化稳定性
DOI：
10.1073/pnas.0306366101
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发表时间：
2004-03-30
影响因子：
11.1
通讯作者：
Redfield, RJ
中科院分区：
文献类型：
--
作者：
Bakkali, M;Chen, TY;Redfield, RJ
流感嗜血杆菌的DNA摄取信号序列（USS）在其基因组中高度过量表达（核心序列AAGTGCGGT的1，471个拷贝），含有USS的DNA片段优先被感受态细胞摄取。由于这种偏好有利于同种DNA的摄取，USS通常被认为是细菌中的一种配偶识别系统，作为物种特异性屏障，阻止不相关DNA的摄取。然而，H.流感病毒USS在三种不同的巴氏杆菌科物种（多杀性巴氏杆菌、睡眠嗜血杆菌和伴放线放线杆菌，分别为927、1，205和1，760个拷贝）的基因组中高度过度表达，表明USS并不总是限制交换。所有这些基因组中的USS主要位于编码区，并且在染色体周围没有显示出方向偏好，从而削弱了所提出的USS在转录终止和染色体复制中的功能。同源基因的比对被用来确定个体USS之间的进化关系。大多数H。在至少一个其他物种中发现流感病毒USS具有完全或不完全同源物（USS在同一位置），并且其他物种中的大多数USS在H.流感。这些同源性表明，一个共同的USS的使用是由于遗传的USS为基础的摄取系统从一个共同的祖先巴斯德菌科，它表明，个别USS可以进化稳定的元素，其基因组。该模式与USS进化的分子驱动模型一致，新的USS由突变产生，并通过偏向的DNA摄取系统优先传播到新的基因组。
The DNA-uptake signal sequence (USS) of the bacterium Haemophilus influenzae is highly over-rep resented in its genome (1,471 copies of the core sequence AAGTGCGGT), and DNA fragments containing USS are preferentially taken up by competent cells. Because this bias favors uptake of conspecific DNA, USSs are often considered a kind of mate recognition system in bacteria, acting as species-specific barriers against uptake of unrelated DNA. However, the H. influenzae USS is highly over-rep resented in the genomes of three otherwise-divergent Pasteurellaceae species (Pasteurella multocida, Haemophilus somnus, and Actinobacillus actinomycetemcomitans, 927, 1,205, and 1,760 copies, respectively), suggesting that USSs do not always limit exchange. USSs in all these genomes are mainly in coding regions and show no orientation bias around the chromosome, weakening proposed USS functions in transcription termination and chromosome replication. Alignment of homologous genes was used to determine evolutionary relationships between individual USSs. Most H. influenzae USSs were found to have perfect or imperfect homologs (USS at the same location) in at least one other species, and most USSs in the other species had perfect or imperfect homologs in H. influenzae. These homologies suggest that the use of a common USS is due to inheritance of the USS-based uptake system from a common ancestor of the Pasteurellaceae, and it indicates that individual USSs can be evolutionarily stable elements of their genomes. The pattern is consistent with a molecular drive model of USS evolution, with new USSs arising by mutation and preferentially spread to new genomes by the biased DNA-uptake system.