Cyclic Di-AMP Impairs Potassium Uptake Mediated by a Cyclic Di-AMP Binding Protein in Streptococcus pneumoniae
Cyclic Di-AMP Impairs Potassium Uptake Mediated by a Cyclic Di-AMP Binding Protein in Streptococcus pneumoniae
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DOI：
10.1128/jb.01041-13
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发表时间：
2014-02-01
影响因子：
3.2
通讯作者：
Bai, Guangchun
中科院分区：
文献类型：
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作者：
Bai, Yinlan;Yang, Jun;Bai, Guangchun
环二-AMP (c-di-AMP) 已被证明作为第二信使在细菌生理学和感染中发挥重要作用。然而，对信号如何转导的理解仍然有限。此前，我们在革兰氏阳性病原体肺炎链球菌中鉴定了一种二腺苷酸环化酶和两种 c-di-AMP 磷酸二酯酶。在这项研究中，我们使用 c-di-AMP 亲和层析鉴定了肺炎链球菌中的 c-di-AMP 结合蛋白 (CabP)。我们证明，CabP 特异性结合 c-di-AMP，并且这种相互作用不会因与其他核苷酸竞争而中断，包括 ATP、cAMP、AMP、磷酸腺苷 (pApA) 和环二 GMP (c-di-GMP)。通过使用细菌双杂交系统和基因诱变，我们表明 CabP 直接与钾转运蛋白 (SPD_0076) 相互作用，并且这两种蛋白都是肺炎球菌在低钾浓度培养基中生长所必需的。有趣的是，肺炎球菌中 c-di-AMP 升高会损害 CabP 和 SPD_0076 之间的相互作用以及钾摄取效率。这些结果建立了直接的 c-di-AMP 介导的信号通路，可调节肺炎球菌钾的摄取。
Cyclic di-AMP (c-di-AMP) has been shown to play important roles as a second messenger in bacterial physiology and infections. However, understanding of how the signal is transduced is still limited. Previously, we have characterized a diadenylate cyclase and two c-di-AMP phosphodiesterases in Streptococcus pneumoniae, a Gram-positive pathogen. In this study, we identified a c-di-AMP binding protein (CabP) in S. pneumoniae using c-di-AMP affinity chromatography. We demonstrated that CabP specifically bound c-di-AMP and that this interaction could not be interrupted by competition with other nucleotides, including ATP, cAMP, AMP, phosphoadenylyl adenosine (pApA), and cyclic di-GMP (c-di-GMP). By using a bacterial two-hybrid system and genetic mutagenesis, we showed that CabP directly interacted with a potassium transporter (SPD_ 0076) and that both proteins were required for pneumococcal growth in media with low concentrations of potassium. Interestingly, the interaction between CabP and SPD_ 0076 and the efficiency of potassium uptake were impaired by elevated c-di-AMP in pneumococci. These results establish a direct c-di-AMP-mediated signaling pathway that regulates pneumococcal potassium uptake.