Wakimoto Takayuki, Nakagishi Shiori, Matsukawa Nao, Tani Shuji, Kai Kenji
Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan.
J Nat Prod. 2020 Jun 26;83(6):1876-1884. doi: 10.1021/acs.jnatprod.0c00054. Epub 2020 Jun 2.
LMG19424, a β-rhizobial symbiont of , harbors and quorum sensing (QS), which are the homologous cell-cell communication systems previously identified from the plant pathogen and the human pathogen , respectively. However, there has been no experimental evidence reported that these QS systems function in LMG19424. We identified ()-methyl 3-hydroxymyristate (3-OH MAME) and ()-3-hydroxypentadecan-4-one (C-AHK) as and QS signals, respectively, and characterized these QS systems. The expression of the signal synthase gene and in BL21(DE3) resulted in the high production of 3-OH MAME and C-AHK, respectively. Their structures were elucidated by comparison of EI-MS data and GC/chiral LC retention times with synthetic standards. The deletion of reduced cell motility and increased biofilm formation, and the double deletion of / caused the accumulation of the metal chelator coproporphyrin III in its mutant culture. Although the deletion of and slightly reduced its ability to nodulate on aseptically grown seedlings of , there was no significant difference in nodule formation between LMG19424 and its QS mutants when commercial soils were used. Taken together, this is the first example of the simultaneous production of 3-OH MAME/C-AHK as QS signals in a bacterial species, and the importance of the / QS systems in the saprophytic stage of LMG19424 is suggested.
LMG19424是[某种植物]的一种β-根瘤菌共生体，含有[两种群体感应系统名称]和[另一种群体感应系统名称]群体感应（QS），它们分别是先前从植物病原体[病原体名称1]和人类病原体[病原体名称2]中鉴定出的同源细胞间通讯系统。然而，尚无实验证据报道这些QS系统在LMG19424中发挥作用。我们分别鉴定出（）-甲基3-羟基肉豆蔻酸（3-OH MAME）和（）-3-羟基十五烷-4-酮（C-AHK）作为[两种群体感应系统名称]和[另一种群体感应系统名称]的QS信号，并对这些QS系统进行了表征。信号合酶基因[基因名称1]和[基因名称2]在BL21(DE3)中的表达分别导致3-OH MAME和C-AHK的高产量。通过将EI-MS数据以及GC/手性LC保留时间与合成标准品进行比较，阐明了它们的结构。[基因名称1]的缺失降低了细胞运动性并增加了生物膜形成，而[基因名称1]/[基因名称2]的双缺失导致其突变体培养物中金属螯合剂粪卟啉原III的积累。尽管[基因名称1]和[基因名称2]的缺失略微降低了其在无菌培养的[植物名称]幼苗上结瘤的能力，但在使用商业土壤时，LMG19424与其QS突变体之间的结瘤形成没有显著差异。综上所述，这是细菌物种中同时产生3-OH MAME/C-AHK作为QS信号的首个实例，并表明了[两种群体感应系统名称]/[另一种群体感应系统名称]QS系统在LMG19424腐生阶段的重要性。
