Cyclic-di-AMP is a nucleotide second messenger present in Gram-positive bacteria and some Gram-negative bacteria and Archaea. The intracellular concentration of cyclic-di-AMP is adjusted in response to environmental and cellular cues, primarily through the activities of synthesis and degradation enzymes. It performs its role by binding to protein and riboswitch receptors, many of which contribute to osmoregulation. Imbalances in cyclic-di-AMP can lead to pleiotropic phenotypes, affecting aspects such as growth, biofilm formation, virulence and resistance to osmotic, acid and antibiotic stressors. This review focuses on cyclic-di-AMP signalling in lactic acid bacteria (LAB) incorporating recent experimental discoveries and presenting an analysis of signalling components from a variety of LAB including those found in food, and commensal, probiotic and pathogenic species. All LAB possess enzymes for the synthesis and degradation of cyclic-di-AMP, but they are highly variable with regards to the receptors they possess. Studies in Lactococcus and Streptococcus have revealed a conserved function for c-di-AMP in inhibiting the transport of potassium and glycine betaine, either through direct binding to transporters or to a transcriptional regulator. Structural analysis of several cyclic-di-AMP receptors from LAB has also provided insights into how this nucleotide exerts its influence.

中文翻译：

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乳酸菌中的环二 AMP 信号传导

Cyclic-di-AMP 是存在于革兰氏阳性细菌和一些革兰氏阴性细菌和古细菌中的核苷酸第二信使。环二磷酸腺苷的细胞内浓度主要通过合成酶和降解酶的活性来响应环境和细胞信号进行调整。它通过与蛋白质和核糖开关受体结合来发挥其作用，其中许多受体有助于渗透压调节。环二磷酸腺苷的不平衡可导致多效性表型，影响生长、生物膜形成、毒力以及对渗透、酸和抗生素应激源的抵抗力等方面。本综述重点关注乳酸菌 (LAB) 中的环二 AMP 信号传导，结合最近的实验发现，并对各种 LAB 中的信号成分进行分析，包括食品和共生细菌中发现的成分。益生菌和致病菌种。所有 LAB 都具有合成和降解环二 AMP 的酶，但它们所具有的受体差异很大。对乳球菌和链球菌的研究表明，c-di-AMP 通过直接与转运蛋白或转录调节因子结合，抑制钾和甘氨酸甜菜碱的转运，具有保守功能。对 LAB 中的几种环二 AMP 受体的结构分析也为了解这种核苷酸如何发挥其影响提供了见解。对乳球菌和链球菌的研究表明，c-di-AMP 通过直接与转运蛋白或转录调节因子结合，抑制钾和甘氨酸甜菜碱的转运，具有保守功能。对 LAB 中的几种环二 AMP 受体的结构分析也为了解这种核苷酸如何发挥其影响提供了见解。对乳球菌和链球菌的研究表明，c-di-AMP 通过直接与转运蛋白或转录调节因子结合，抑制钾和甘氨酸甜菜碱的转运，具有保守功能。对 LAB 中的几种环二 AMP 受体的结构分析也为了解这种核苷酸如何发挥其影响提供了见解。