LuxR solos in Photorhabdus species
LuxR solos in Photorhabdus species
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DOI：
10.3389/fcimb.2014.00166
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发表时间：
2014-11-01
影响因子：
5.7
通讯作者：
Heermann, Ralf
中科院分区：
文献类型：
--
作者：
Brameyer, Sophie;Kresovic, Darko;Heermann, Ralf
细菌通过小的可扩散分子进行交流，以调节群体协调行为，这一过程被称为群体感应。革兰氏阴性菌的基本分子群体感应系统由产生酰基高丝氨酸内酯（acyl-homoserine lactones，AHLs）作为信号分子的Luxl型自诱导物合酶和检测AHLs以控制特定基因表达的LuxR型受体组成。然而，许多变形菌具有一个或多个未配对的LuxR型受体，其缺乏同源的Luxl样合酶，称为LuxR solos。肠道和昆虫病原细菌属Photorhabdus窝藏非常高的LuxR独奏，比任何其他已知的细菌，都缺乏一个LuxL样合成酶。在这里，我们专注于在三个已知的Photorhabdus物种使用生物信息学分析的存在和不同类型的LuxR独奏。通常，LuxR型受体感应AHLs的N-末端信号结合结构域（SBD）具有六个保守氨基酸的基序，其对于信号分子的结合和特异性是重要的。然而，该基序在大多数光杆状病毒特异性LuxR solo中发生改变，表明使用了除AHLs之外的其他信号分子。此外，所有光杆状菌物种都含有至少一个LuxR单体，其具有完整的AHL结合基序，这可能允许感测其他细菌的AHL的能力。此外，所有三个物种都具有由不同AHL-内酯酶和AHL-酰化酶的存在引起的高AHL降解活性，揭示了对其他细菌的高群体淬灭活性。然而，大多数其他LuxR solos在Photorhabdus有一个N-末端所谓的PAS 4-结构域，而不是AHL-结合结构域，含有不同的氨基酸基序比AHL-传感器，这可能允许识别的高度可变范围的信号分子，可以感测到除了AHL。这些PAS 4-LuxR solo被认为参与宿主感知，因此参与界间信号传导。总的来说，Photorhabdus物种是研究通过LuxR solos进行细菌通信及其在共生和致病生活方式中的作用的完美模式生物。
Bacteria communicate via small diffusible molecules to mediate group-coordinated behavior, a process designated as quorum sensing. The basic molecular quorum sensing system of Gram-negative bacteria consists of a Luxl-type autoinducer synthase producing acyl-homoserine lactones (AHLs) as signaling molecules, and a LuxR-type receptor detecting the AHLs to control expression of specific genes. However, many proteobacteria possess one or more unpaired LuxR-type receptors that lack a cognate Luxl-like synthase, referred to as LuxR solos. The enteric and insect pathogenic bacteria of the genus Photorhabdus harbor an extraordinarily high number of LuxR solos, more than any other known bacteria, and all lack a Luxl-like synthase. Here, we focus on the presence and the different types of LuxR solos in the three known Photorhabdus species using bioinformatics analyses. Generally, the N-terminal signal-binding domain (SBD) of LuxR-type receptors sensing AHLs have a motif of six conserved amino acids that is important for binding and specificity of the signaling molecule. However, this motif is altered in the majority of the Photorhabdus-specific LuxR solos, suggesting the use of other signaling molecules than AHLs. Furthermore, all Photorhabdus species contain at least one LuxR solo with an intact AHL-binding motif, which might allow the ability to sense AHLs of other bacteria. Moreover, all three species have high AHL-degrading activity caused by the presence of different AHL-lactonases and AHL-acylases, revealing a high quorum quenching activity against other bacteria. However, the majority of the other LuxR solos in Photorhabdus have a N-terminal so-called PAS4-domain instead of an AHL-binding domain, containing different amino acid motifs than the AHL-sensors, which potentially allows the recognition of a highly variable range of signaling molecules that can be sensed apart from AHLs. These PAS4-LuxR solos are proposed to be involved in host sensing, and therefore in inter-kingdom signaling. Overall, Photorhabdus species are perfect model organisms to study bacterial communication via LuxR solos and their role for a symbiotic and pathogenic life style.