Nitrogen oxyanion-dependent dissociation of a two-component complex that regulates bacterial nitrate assimilation.
Nitrogen oxyanion-dependent dissociation of a two-component complex that regulates bacterial nitrate assimilation.
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DOI：
10.1074/jbc.m113.459032
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发表时间：
2013-10-11
期刊：
影响因子：
--
通讯作者：
Gates AJ
中科院分区：
文献类型：
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作者：
Luque-Almagro VM;Lyall VJ;Ferguson SJ;Roldán MD;Richardson DJ;Gates AJ
背景资料：氮氧阴离子响应的双组分调节剂，控制同化硝酸盐代谢的异养细菌的特点很差。结果：nasT和nasS基因编码一种调节复合物，该复合物在感知硝酸盐/亚硝酸盐时解离，释放RNA结合蛋白NasT。结论：NasS-NasT是一种双组分的硝酸盐/亚硝酸盐感知调节剂。意义：首次证明了NasS和NasT之间的硝酸盐/亚硝酸盐敏感性相互作用。氮是生长的必需营养素，并且在许多环境中以铵和硝酸盐的形式容易被微生物利用。这两种离子都具有环境意义，因为在农业土壤上持续使用无机肥料。具有同化硝酸盐/亚硝酸盐还原酶系统（NAS）的各种细菌可以在铵受限时使用硝酸盐或亚硝酸盐作为生长的唯一氮源。在副球菌中，NAS表达的途径特异性双组分调节剂由nasT和nasS基因编码。在这里，我们表明，推定的RNA结合蛋白NasT是一个积极的调节所必需的nas基因簇（即nasABGHC）的表达。相比之下，需要氮氧阴离子结合传感器（NasS）的nas基因表达的硝酸盐/亚硝酸盐响应控制。NasS和NasT蛋白共纯化为稳定的异源四聚体调节复合物NasS-NasT。这种蛋白质-蛋白质相互作用对硝酸盐和亚硝酸盐敏感，这导致NasS-NasT复合物解离成单体NasS和NasT的寡聚体形式。已显示NasT结合nasA的前导RNA。因此，在从复合物释放后，正调节因子NasT自由地上调nas基因表达。
Background: Nitrogen oxyanion-responsive two-component regulators that control assimilatory nitrate metabolism in heterotrophic bacteria are poorly characterized. Results: The nasT and nasS genes encode a regulatory complex that dissociates upon sensing nitrate/nitrite, releasing the RNA-binding protein NasT. Conclusion: NasS-NasT is a two-component regulator for nitrate/nitrite perception. Significance: A nitrate/nitrite-sensitive interaction between NasS and NasT has been demonstrated for the first time. Nitrogen is an essential nutrient for growth and is readily available to microbes in many environments in the form of ammonium and nitrate. Both ions are of environmental significance due to sustained use of inorganic fertilizers on agricultural soils. Diverse species of bacteria that have an assimilatory nitrate/nitrite reductase system (NAS) can use nitrate or nitrite as the sole nitrogen source for growth when ammonium is limited. In Paracoccus denitrificans, the pathway-specific two-component regulator for NAS expression is encoded by the nasT and nasS genes. Here, we show that the putative RNA-binding protein NasT is a positive regulator essential for expression of the nas gene cluster (i.e. nasABGHC). By contrast, a nitrogen oxyanion-binding sensor (NasS) is required for nitrate/nitrite-responsive control of nas gene expression. The NasS and NasT proteins co-purify as a stable heterotetrameric regulatory complex, NasS-NasT. This protein-protein interaction is sensitive to nitrate and nitrite, which cause dissociation of the NasS-NasT complex into monomeric NasS and an oligomeric form of NasT. NasT has been shown to bind the leader RNA for nasA. Thus, upon liberation from the complex, the positive regulator NasT is free to up-regulate nas gene expression.