Cyclic Di-AMP Homeostasis in Bacillus subtilis BOTH LACK AND HIGH LEVEL ACCUMULATION OF THE NUCLEOTIDE ARE DETRIMENTAL FOR CELL GROWTH
Cyclic Di-AMP Homeostasis in Bacillus subtilis BOTH LACK AND HIGH LEVEL ACCUMULATION OF THE NUCLEOTIDE ARE DETRIMENTAL FOR CELL GROWTH
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DOI：
10.1074/jbc.m112.395491
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发表时间：
2013-01-18
影响因子：
4.8
通讯作者：
Stuelke, Joerg
中科院分区：
文献类型：
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作者：
Mehne, Felix M. P.;Gunka, Katrin;Stuelke, Joerg
革兰氏阳性土壤细菌枯草芽孢杆菌的基因组编码三种潜在的二腺苷环化酶，它们可能合成信号核苷酸环二AMP(c-di-AMP)。这些酶在不同的条件下在不同的细胞室中表达，并定位于细胞中的不同位置。在这里，我们展示了到目前为止尚未鉴定的酶CDAA(以前称为YbbP)和CDAS(YojJ)的二腺苷环化酶活性。我们的工作证实了c-di-AMP对枯草杆菌的生长是必不可少的，并表明过量的分子也对细菌有害。一些证据表明，二腺苷环化酶CDAA是参与细胞壁代谢的保守的基本CDA-GLM模块的一部分。相反，CDAS酶似乎为孢子提供c-di-AMP。大量c-二-AMP的积累会损害枯草杆菌的生长，并导致异常卷曲细胞的形成。升高的镁浓度可以部分抑制这种表型。这些观察结果表明，c-二-AMP干扰了肽聚糖的合成机制。二腺苷环化酶的活性受不同的分子机制控制。CDAA是由与CdaR(YbbR)蛋白的调节相互作用刺激的。相比之下，CDA的活性似乎受到内在的限制，单个氨基酸的取代就足以大幅提高酶的活性。综上所述，我们的结果支持c-diamp在枯草杆菌中发挥重要作用的观点，并建议必须严格控制核苷酸水平。
The genome of the Gram-positive soil bacterium Bacillus subtilis encodes three potential diadenylate cyclases that may synthesize the signaling nucleotide cyclic di-AMP (c-di-AMP). These enzymes are expressed under different conditions in different cell compartments, and they localize to distinct positions in the cell. Here we demonstrate the diadenylate cyclase activity of the so far uncharacterized enzymes CdaA (previously known as YbbP) and CdaS (YojJ). Our work confirms that c-di-AMP is essential for the growth of B. subtilis and shows that an excess of the molecule is also harmful for the bacteria. Several lines of evidence suggest that the diadenylate cyclase CdaA is part of the conserved essential cda-glm module involved in cell wall metabolism. In contrast, the CdaS enzyme seems to provide c-di-AMP for spores. Accumulation of large amounts of c-di-AMP impairs the growth of B. subtilis and results in the formation of aberrant curly cells. This phenotype can be partially suppressed by elevated concentrations of magnesium. These observations suggest that c-di-AMP interferes with the peptidoglycan synthesis machinery. The activity of the diadenylate cyclases is controlled by distinct molecular mechanisms. CdaA is stimulated by a regulatory interaction with the CdaR (YbbR) protein. In contrast, the activity of CdaS seems to be intrinsically restricted, and a single amino acid substitution is sufficient to drastically increase the activity of the enzyme. Taken together, our results support the idea of an important role for c-di-AMP in B. subtilis and suggest that the levels of the nucleotide have to be tightly controlled.