Selection for chromosome architecture in bacteria
Selection for chromosome architecture in bacteria
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DOI：
10.1007/s00239-005-0192-2
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发表时间：
2006-05-01
影响因子：
3.9
通讯作者：
Lawrence, Jeffrey G.
中科院分区：
文献类型：
--
作者：
Hendrickson, Heather;Lawrence, Jeffrey G.
细菌染色体是巨大的聚合物，其忠实的复制和分离对细胞存活至关重要。蛋白质如FtsK能够单向移动到复制末端，并在细胞分裂过程中引导DNA易位到适当的子细胞中，这需要细菌基因组保持染色体有序复制和分离的结构。我们认为，位于复制末端的蛋白质利用链偏置序列，在一条DNA链上过度表达，并且选择随着到复制末端的距离减小而增加。我们报告了一个通用的方法来检测这些架构赋予序列（AIMS），并确定了AIMS在几乎所有的细菌基因组。它们在前导链上的丰度增加和在滞后链上朝向复制末端的丰度减少不是突变偏倚变化的结果;相反，它们反映了AIMS的长期阳性选择的梯度。AIMS模式在相关细菌的基因组中的维持与它们在单个基因中的位置无关，这表明AIMS在基因组生物学中具有良好的保守作用。AIMS丰度从复制起点到末端的稳定梯度表明，复制体作为选择的靶点，其中染色体结构的选择导致基因顺序的维持和复制体内缺乏高频DNA倒位。
Bacterial chromosomes are immense polymers whose faithful replication and segregation are crucial to cell survival. The ability of proteins such as FtsK to move unidirectionally toward the replication terminus, and direct DNA translocation into the appropriate daughter cell during cell division, requires that bacterial genomes maintain an architecture for the orderly replication and segregation of chromosomes. We suggest that proteins that locate the replication terminus exploit strand-biased sequences that are overrepresented on one DNA strand, and that selection increases with decreased distance to the replication terminus. We report a generalized method for detecting these architecture imparting sequences (AIMS) and have identified AIMS in nearly all bacterial genomes. Their increased abundance on leading strands and decreased abundance on lagging strands toward replication termini are not the result of changes in mutational bias; rather, they reflect a gradient of long-term positive selection for AIMS. The maintenance of the pattern of AIMS across the genomes of related bacteria independent of their positions within individual genes suggests a well-conserved role in genome biology. The stable gradient of AIMS abundance from replication origin to terminus suggests that the replicore acts as a target of selection, where selection for chromosome architecture results in the maintenance of gene order and in the lack of high-frequency DNA inversion within replicores.