Supercoiling of an excised genomic island represses effector gene expression to prevent activation of host resistance.
Supercoiling of an excised genomic island represses effector gene expression to prevent activation of host resistance.
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切除的基因组岛的超螺旋抑制效应基因表达，以防止宿主抗性激活。
DOI：
10.1111/mmi.14111
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发表时间：
2018-11
影响因子：
3.6
通讯作者：
Arnold DL
中科院分区：
文献类型：
--
作者：
Neale HC;Jackson RW;Preston GM;Arnold DL
植物病原细菌假单胞菌（Pseudomonaserichinagev. pv.）引起菜豆晕斑病的菜豆生根瘤菌（phaseolicola）含有106 kb的基因组岛PPHGI-1。PPHGI-1携带一个基因avrPphB，它编码一种效应蛋白，在某些豆类品种中引发抗性反应。先前的研究表明，当PPHGI-1从细菌染色体上切除时，avrPphB被下调，因此病原体避免触发宿主的防御机制。在这里，我们研究avrPphB的下调是否由PPHGI-1的超螺旋引起。我们还研究了PPHGI-1编码的1A型拓扑异构酶TopB 3对植物中岛屿稳定性和细菌致病性的影响。超螺旋抑制剂显著增加avrPphB的表达，但不影响PPHGI-1的切除。topB 3的插入突变体显示avrPphB表达增加和PPHGI-1切除增加，以及抗性和感病菜豆品种的群体增长减少。这些结果表明拓扑异构酶在细菌编码的基因组岛的维持和稳定性中起重要作用，并证明一旦岛被切除，超螺旋参与效应基因的下调，从而使病原体阻止宿主防御反应的进一步激活。
The plant pathogen Pseudomonas syringae pv. phaseolicola, which causes halo blight disease of beans, contains a 106 kb genomic island PPHGI‐1. PPHGI‐1 carries a gene, avrPphB, which encodes an effector protein that triggers a resistance response in certain bean cultivars. Previous studies have shown that when PPHGI‐1 is excised from the bacterial chromosome, avrPphB is downregulated and therefore the pathogen avoids triggering the host’s defence mechanism. Here, we investigate whether the downregulation of avrPphB is caused by the supercoiling of PPHGI‐1. We also investigate the effect of a PPHGI‐1‐encoded type 1A topoisomerase, TopB3, on island stability and bacterial pathogenicity in the plant. Supercoiling inhibitors significantly increased the expression of avrPphB but did not affect the excision of PPHGI‐1. An insertional mutant of topB3 displayed an increase in avrPphB expression and an increase in PPHGI‐1 excision as well as reduced population growth in resistant and susceptible cultivars of bean. These results suggest an important role for topoisomerases in the maintenance and stability of a bacterial‐encoded genomic island and demonstrate that supercoiling is involved in the downregulation of an effector gene once the island has been excised, allowing the pathogen to prevent further activation of the host defence response.
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影响因子：
3.6
作者：
Perez-Cheeks BA;Lee C;Hayama R;Marians KJ
通讯作者：
Marians KJ
影响因子：
14.9
作者：
Ferrandiz, Maria-Jose;Martin-Galiano, Antonio J.;de la Campa, Adela G.
通讯作者：
de la Campa, Adela G.
影响因子：
6.7
作者：
Godfrey, Scott A. C.;Lovell, Helen C.;Arnold, Dawn L.
通讯作者：
Arnold, Dawn L.
病原体中基因组岛的低频持续储层可确保岛屿的生存并改善易感宿主的病原体适应性。
影响因子：
5.1
作者：
Neale HC;Laister R;Payne J;Preston G;Jackson RW;Arnold DL
通讯作者：
Arnold DL
影响因子：
2.6
作者：
Neale, Helen C.;Slater, Ross T.;Arnold, Dawn L.
通讯作者：
Arnold, Dawn L.