Martínez-Alcantar Lorena, Orozco Gabriela, Díaz-Pérez Alma Laura, Villegas Javier, Reyes-De la Cruz Homero, García-Pineda Ernesto, Campos-García Jesús
Laboratorio de Biotecnología Microbiana, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico.
Laboratorio de Interacción Suelo, Planta, Microorganismo, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico.
Front Microbiol. 2021 Nov 16;12:785112. doi: 10.3389/fmicb.2021.785112. eCollection 2021.
The pathogenic bacterium possesses high metabolic versatility, with its effectiveness to cause infections likely due to its well-regulated genetic content. PAO1 has at least six paralogous genes, which have been implicated in fatty acid (FA) degradation and pathogenicity. In this study, we used mutagenesis and a functional approach in PAO1 to determine the roles of the gene in acyclic terpene (AT) and FA assimilation and on pathogenicity. The results indicate that encodes a terpenoyl-CoA synthetase utilized for AT and FA assimilation. Additionally, mutations in paralogs led to the modification of the quorum-sensing / systems, as well as the content of virulence factors pyocyanin, biofilm, rhamnolipids, lipopolysaccharides (LPS), and polyhydroxyalkanoates. In a pathogenicity model, culture supernatants from the 24-h-grown single mutant increased lethality compared to the PAO1 wild-type (WT) strain; however, the double mutants , , and and single mutant increased worm survival. A correlation analysis indicated an interaction between worm death by the PAO1 strain, the mutation, and the virulence factor LPS. Fatty acid methyl ester (FAME) analysis of LPS revealed that a proportion of the LPS and FA on lipid A were modified by the mutation, suggesting that FadD4 is also involved in the synthesis/degradation and modification of the lipid A component of LPS. LPS isolated from the mutant and double mutants and showed a differential behavior to induce an increase in body temperature in rats injected with LPS compared to the WT strain or from the and mutants. In agreement, LPS isolated from the mutant and double mutants and increased the induction of IL-8 in rat sera, but IL1-β cytokine levels decreased in the double mutants and . The results indicate that the genes are implicated in the degree of pathogenicity of PAO1 induced by LPS-lipid A, suggesting that FadD4 contributes to the removal of acyl-linked FA from LPS, rendering modification in its immunogenic response associated to Toll-like receptor TLR4. The genetic redundancy of is important for bacterial adaptability and pathogenicity over the host.
该病原菌具有高度的代谢多样性，其引发感染的有效性可能归因于其调控良好的遗传内容。PAO1至少有六个旁系同源基因，这些基因与脂肪酸（FA）降解和致病性有关。在本研究中，我们在PAO1中采用诱变和功能方法来确定该基因在无环萜烯（AT）和FA同化以及致病性方面的作用。结果表明，该基因编码一种用于AT和FA同化的萜烯酰辅酶A合成酶。此外，旁系同源基因中的突变导致群体感应/系统的改变，以及毒力因子绿脓菌素、生物膜、鼠李糖脂、脂多糖（LPS）和聚羟基脂肪酸酯的含量变化。在致病性模型中，与PAO1野生型（WT）菌株相比，24小时培养的单一突变体的培养上清液增加了致死率；然而，双突变体、和以及单一突变体增加了蠕虫的存活率。相关性分析表明，PAO1菌株导致的蠕虫死亡、突变和毒力因子LPS之间存在相互作用。LPS的脂肪酸甲酯（FAME）分析表明，LPS和脂质A上的一部分FA因突变而发生了修饰，这表明FadD4也参与了LPS脂质A成分的合成/降解和修饰。与WT菌株或和突变体相比，从突变体和双突变体和中分离出的LPS在注射LPS的大鼠中诱导体温升高的行为有所不同。同样，从突变体和双突变体和中分离出的LPS增加了大鼠血清中IL-8的诱导，但双突变体和中的IL1-β细胞因子水平降低。结果表明，这些基因与LPS-脂质A诱导的PAO1致病性程度有关，这表明FadD4有助于从LPS中去除酰基连接的FA，从而改变其与Toll样受体TLR4相关的免疫原性反应。的基因冗余对于细菌在宿主上的适应性和致病性很重要。
