Genome Reduction by Deletion of Paralogs in the Marine Cyanobacterium Prochlorococcus
Genome Reduction by Deletion of Paralogs in the Marine Cyanobacterium Prochlorococcus
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DOI：
10.1093/molbev/msr081
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发表时间：
2011-10-01
影响因子：
10.7
通讯作者：
Hughes, Austin L.
中科院分区：
文献类型：
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作者：
Luo, Haiwei;Friedman, Robert;Hughes, Austin L.
海洋蓝藻原绿球藻属的几个分离株的基因组大小比密切相关的聚球藻属的基因组大小小。为了测试蛋白质编码基因的丢失是否有助于原绿球藻基因组大小的减少，我们重建了一个强有力的支持12原绿球藻基因组和9聚球藻基因组的同源性的基因家族进化的事件。明显的是，更多的事件发生在原绿球藻比聚球藻的基因家族内的旁系同源物的损失和整个基因家族的损失。两属基因组中非祖先基因家族的数量与基因组岛（GI）的程度呈正相关，与水平基因转移（HGT）与GI相关的假设一致。然而，即使当只有分离物具有可比程度的地理标志进行了比较，显着更多的事件的基因家族的损失和paralcohol损失被认为是在原绿球藻比聚球藻，这意味着HGT是不是两个属之间的基因组大小差异的主要原因。
Several isolates of the marine cyanobacterial genus Prochlorococcus have smaller genome sizes than those of the closely related genus Synechococcus. In order to test whether loss of protein-coding genes has contributed to genome size reduction in Prochlorococcus, we reconstructed events of gene family evolution over a strongly supported phylogeny of 12 Prochlorococcus genomes and 9 Synechococcus genomes. Significantly, more events both of loss of paralogs within gene families and of loss of entire gene families occurred in Prochlorococcus than in Synechococcus. The number of nonancestral gene families in genomes of both genera was positively correlated with the extent of genomic islands (GIs), consistent with the hypothesis that horizontal gene transfer (HGT) is associated with GIs. However, even when only isolates with comparable extents of GIs were compared, significantly more events of gene family loss and of paralog loss were seen in Prochlorococcus than in Synechococcus, implying that HGT is not the primary reason for the genome size difference between the two genera.