Heterogeneic dynamics of the structures of multiple gene clusters in two pathogenetically different lines originating from the same phytoplasma
Heterogeneic dynamics of the structures of multiple gene clusters in two pathogenetically different lines originating from the same phytoplasma
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DOI：
10.1089/dna.2007.0654
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发表时间：
2008-04-01
影响因子：
3.1
通讯作者：
Namba, Shigetou
中科院分区：
文献类型：
--
作者：
Arashida, Ryo;Kakizawa, Shigeyuki;Namba, Shigetou
植原体是由昆虫传播的韧皮部限制的植物病原体，与数百种植物物种的疾病有关。尽管植原体基因组的大小很小，但它们具有丰富的重复序列，这是由于几个基因被编码为多个拷贝。这些多个基因存在于一个基因簇中，即潜在的移动的单位（PMU）。PMU存在于植原体基因组中的几个不同区域。由PMU编码的多拷贝基因（本文称为移动的单位基因[MUG]）和基因组中其他地方的类似基因（本文称为基础基因[FUG]）基于它们的注释可能具有相同的功能。在这份手稿中，我们显示的证据表明，MUG和FUG不集群在同一分支。每个MUG都在一个短分支长度的簇中，这表明MUG是最近分化的旁系同源物，而FUG的起源与MUG的起源不同。我们还比较了“Candidatus Phytoplasma asteris”OY株的两个衍生系（严重症状系W（OY-W）和轻度症状系M（OY-M））中lplA基因周围的基因组结构。OY-W和OY-M的lplA基因上游的核苷酸序列的基因组织显著不同。tra 5插入序列是PMU的一个元件，仅在OY-W的该区域中发现。这些结果表明，转座的整个PMU和PMU部分经常发生在OY植原体基因组。OY-W和OY-M的致病性差异可能是由于PMUs的复制和转座，随后发生基因组重排所致。
Phytoplasmas are phloem-limited plant pathogens that are transmitted by insect vectors and are associated with diseases in hundreds of plant species. Despite their small sizes, phytoplasma genomes have repeat-rich sequences, which are due to several genes that are encoded as multiple copies. These multiple genes exist in a gene cluster, the potential mobile unit (PMU). PMUs are present at several distinct regions in the phytoplasma genome. The multicopy genes encoded by PMUs (herein named mobile unit genes [MUGs]) and similar genes elsewhere in the genome (herein named fundamental genes [FUGs]) are likely to have the same function based on their annotations. In this manuscript we show evidence that MUGs and FUGs do not cluster together within the same clade. Each MUG is in a cluster with a short branch length, suggesting that MUGs are recently diverged paralogs, whereas the origin of FUGs is different from that of MUGs. We also compared the genome structures around the lplA gene in two derivative lines of the 'Candidatus Phytoplasma asteris' OY strain, the severe-symptom line W (OY-W) and the mild-symptom line M (OY-M). The gene organizations of the nucleotide sequences upstream of the lplA genes of OY-W and OY-M were dramatically different. The tra5 insertion sequence, an element of PMUs, was found only in this region in OY-W. These results suggest that transposition of entire PMUs and PMU sections has occurred frequently in the OY phytoplasma genome. The difference in the pathogenicities of OY-W and OY-M might be caused by the duplication and transposition of PMUs, followed by genome rearrangement.