Quorum Sensing and LuxR Solos in Photorhabdus.
Quorum Sensing and LuxR Solos in Photorhabdus.
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DOI：
10.1007/82_2016_28
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发表时间：
2016-11
影响因子：
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通讯作者：
Sophie Brameyer;R. Heermann
中科院分区：
文献类型：
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作者：
Sophie Brameyer;R. Heermann
细菌通过小的可扩散分子来介导群体协调行为的通信通常被称为“群体感应”。革兰氏阴性菌的原型群体感应系统由产生酰基高丝氨酸内酯（AHL）作为信号的LuxI型自诱导物合酶和检测AHL以控制特定基因表达的LuxR型受体组成。然而，许多细菌具有LuxR同源物，但缺乏同源的LuxI型AHL合酶。这些LuxR型受体被称为“LuxR孤儿”或“孤独”。Photorhabdusall属的昆虫病原细菌都含有大量的LuxR solos，比迄今为止检测的任何其他细菌都多。两种新的群体感应系统被发现调节细胞聚集在Photorhabdus，从而影响致病性。在Photorhabdus luminescens和Photorhabdus temperatillus LuxR中，单独的PluR感测α-吡喃酮，称为“吡喃酮”，而不是AHL，其由吡喃酮合成酶PpyS产生。相比之下，Photorhabdus asybiotica，一种密切相关的昆虫和人类病原体，具有PluR同系物PauR，其感测由DarABC途径产生的二烷基间苯二酚以调节致病性。所有三个Photorhabdusspecies港口至少有一个LuxR独奏与完整的AHL结合基序，这也可能允许传感外源AHL。然而，在所有的光杆属物种中，大多数LuxR单体都具有PAS 4信号结合结构域。这些受体被认为是检测真核生物的化合物，并提出参与宿主传感。总的来说，由于它们编码大量的LuxR solos，Photorhabdus属的细菌是研究和鉴定新型细菌通信网络的理想候选者。
Bacterial communication via small diffusible molecules to mediate group-coordinated behaviour is commonly referred to as ‘quorum sensing’. The prototypical quorum sensing system of Gram-negative bacteria consists of a LuxI-type autoinducer synthase that produces acyl-homoserine lactones (AHLs) as signals and a LuxR-type receptor that detects the AHLs to control expression of specific genes. However, many bacteria possess LuxR homologs but lack a cognate LuxI-type AHL-synthase. Those LuxR-type receptors are designated as ‘LuxR orphans’ or ‘solos’. Entomopathogenic bacteria of the genusPhotorhabdusall harbour a large number of LuxR solos, more than any other bacteria examined so far. Two novel quorum sensing systems were found to regulate cell clumping inPhotorhabdusand therefore affect pathogenicity. InPhotorhabdus luminescensandPhotorhabdus temperatathe LuxR solo PluR senses α-pyrones named ‘photopyrones’ instead of AHLs, which are produced by the pyrone synthase PpyS. In contrast,Photorhabdus asymbiotica, a closely related insect and human pathogen, has the PluR homolog PauR, which senses dialkylresorcinols produced by the DarABC pathway to regulate pathogenicity. All threePhotorhabdusspecies harbour at least one LuxR solo with an intact AHL-binding motif, which might also allow sensing of exogenous AHLs. However, the majority of the LuxR solos in allPhotorhabdusspecies have a PAS4 signal-binding domain. These receptors are assumed to detect eukaryotic compounds and are proposed to be involved in host sensing. Overall, because of the large number of LuxR solos they encode, bacteria of the genusPhotorhabdusare ideal candidates to study and to identify novel bacterial communication networks.