PDF(Pubmed)
Abstract：
Cyclic purine nucleotides are important signal transduction molecules across all domains of life. 3\',5\'-cyclic di-adenosine monophosphate (c-di-AMP) has roles in both prokaryotes and eukaryotes, while the signals that adjust intracellular c-di-AMP and the molecular machinery enabling a network-wide homeostatic response remain largely unknown. Here, we present evidence for an acetyl phosphate (AcP)-governed network responsible for c-di-AMP homeostasis through two distinct substrates, the diadenylate cyclase DNA integrity scanning protein (DisA) and its newly identified transcriptional repressor, DasR. Correspondingly, we found that AcP-induced acetylation exerts these regulatory actions by disrupting protein multimerization, thus impairing c-di-AMP synthesis via K66 acetylation of DisA. Conversely, the transcriptional inhibition of disA was relieved during DasR acetylation at K78. These findings establish a pivotal physiological role for AcP as a mediator to balance c-di-AMP homeostasis. Further studies revealed that acetylated DisA and DasR undergo conformational changes that play crucial roles in differentiation. Considering the broad distribution of AcP-induced acetylation in response to environmental stress, as well as the high conservation of the identified key sites, we propose that this unique regulation of c-di-AMP homeostasis may constitute a fundamental property of central circuits in Actinobacteria and thus the global control of cellular physiology.IMPORTANCESince the identification of c-di-AMP is required for bacterial growth and cellular physiology, a major challenge is the cell signals and stimuli that feed into the decision-making process of c-di-AMP concentration and how that information is integrated into the regulatory pathways. Using the bacterium Saccharopolyspora erythraea as a model, we established that AcP-dependent acetylation of the diadenylate cyclase DisA and its newly identified transcriptional repressor DasR is involved in coordinating environmental and intracellular signals, which are crucial for c-di-AMP homeostasis. Specifically, DisA acetylated at K66 directly inactivates its diadenylate cyclase activity, hence the production of c-di-AMP, whereas DasR acetylation at K78 leads to increased disA expression and c-di-AMP levels. Thus, AcP represents an essential molecular switch in c-di-AMP maintenance, responding to environmental changes and possibly hampering efficient development. Therefore, AcP-mediated posttranslational processes constitute a network beyond the usual and well-characterized synthetase/hydrolase governing c-di-AMP homeostasis.
摘要：
环嘌呤核苷酸是跨越生命所有域的重要信号转导分子。3\',5'-环二磷酸腺苷（c-di-AMP）在原核生物和真核生物中均有作用，而调节细胞内c-di-AMP的信号和能够实现网络范围内稳态反应的分子机制仍然很大程度上未知。这里,我们提出的证据表明，乙酰磷酸（AcP）控制的网络负责c-di-AMP稳态通过两个不同的底物，二腺苷酸环化酶DNA完整性扫描蛋白（DisA）及其新发现的转录阻遏物，DasR.相应地,我们发现AcP诱导的乙酰化通过破坏蛋白质多聚化发挥这些调节作用，因此通过DisA的K66乙酰化损害c-di-AMP的合成。相反，在K78的DasR乙酰化过程中，disA的转录抑制得到缓解。这些发现确立了AcP作为平衡c-di-AMP稳态的介质的关键生理作用。进一步的研究表明，乙酰化的DisA和DasR经历构象变化，在分化中起关键作用。考虑到AcP诱导的乙酰化反应对环境胁迫的广泛分布，以及对已确定的关键地点的高度保护，我们认为，这种对c-di-AMP稳态的独特调节可能构成放线菌中央回路的基本特性，从而构成细胞生理学的整体控制。重要性由于c-di-AMP的鉴定是细菌生长和细胞生理学所必需的，一个主要挑战是进入c-di-AMP浓度决策过程的细胞信号和刺激，以及这些信息如何整合到调节途径中。以酵母菌为模型，我们确定二腺苷酸环化酶DisA的AcP依赖性乙酰化及其新鉴定的转录阻遏物DasR参与协调环境和细胞内信号，这对c-di-AMP稳态至关重要。具体来说,在K66乙酰化的DisA直接失活其二腺苷酸环化酶活性，因此，c-di-AMP的生产，而K78处的DasR乙酰化导致disA表达和c-di-AMP水平增加。因此，AcP代表c-di-AMP维持中必不可少的分子开关，应对环境变化，并可能阻碍有效发展。因此,AcP介导的翻译后过程构成了一个网络，超出了控制c-di-AMP稳态的通常且表征良好的合成酶/水解酶。
