EslB is required for cell wall biosynthesis and modification in Listeria monocytogenes
EslB is required for cell wall biosynthesis and modification in Listeria monocytogenes
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单核细胞增生李斯特菌的细胞壁生物合成和修饰需要 EslB
DOI：
10.1101/2020.02.03.932061
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Rismondo J
中科院分区：
文献类型：
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作者：
Rismondo J
溶菌酶是先天免疫系统的重要组成部分。它通过水解细菌的肽聚糖（PG）层起作用。人类病原体单核细胞增生李斯特菌具有内在的溶菌酶抗性。肽聚糖去乙酰化酶PgdA和乙酰转移酶OatA是导致其溶菌酶抗性的两个已知因素。此外，研究表明，ABC转运体成分（这里称为EslABC）的缺失导致溶菌酶抗性降低。它的活性如何与溶菌酶抗性联系起来仍然是未知的。为了进一步研究这一点，我们在单核增生李斯特菌10403S中构建了一株编码ABC转运体膜组分的缺失ineslB菌株。突变体显示溶菌酶的MIC降低了40倍。对PG结构的分析显示，该eslb突变体产生的PG的o -乙酰化水平降低。通过生长和自溶实验，我们发现在含有高浓度糖和内源性细胞溶解增加的培养基中，缺乏EslB表现为生长缺陷。在这些生长条件下，突变体产生的更薄的PG层可能解释了这些表型。此外，突变体存在明显的细胞分裂缺陷，形成了细长的细胞。显微镜分析显示，早期细胞分裂蛋白仍然定位在eslb突变体中，表明下游过程受到干扰。基于我们的研究结果，我们假设EslB影响单核增生乳杆菌细胞壁的生物合成和修饰，因此对维持细胞壁完整性很重要。ABC转运体EslABC与单核增生李斯特菌的内在溶菌酶抗性有关。然而，转运蛋白在这一过程中的确切作用以及在单核增生乳杆菌的生理中所起的作用尚不清楚。通过不同的实验来表征一株EslB，我们发现缺乏EslB不仅影响溶菌酶抗性，还影响内源性细胞裂解、细胞壁生物合成、细胞分裂以及细菌在含有高浓度糖的培养基中生长的能力。我们的研究结果表明，通过一种尚不清楚的机制，EslB是单核增生乳杆菌细胞壁完整性的重要决定因素。
Lysozyme is an important component of the innate immune system. It functions by hydrolyzing the peptidoglycan (PG) layer of bacteria. The human pathogen Listeria monocytogenes is intrinsically lysozyme resistant. The peptidoglycanN-deacetylase PgdA andO-acetyltransferase OatA are two known factors contributing to its lysozyme resistance. Furthermore, it was shown that the absence of components of an ABC transporter, referred to here as EslABC, leads to reduced lysozyme resistance. How its activity is linked to lysozyme resistance is still unknown. To investigate this further, a strain with a deletion ineslB, coding for a membrane component of the ABC transporter, was constructed in L. monocytogenes strain 10403S. TheeslBmutant showed a 40-fold reduction in the MIC to lysozyme. Analysis of the PG structure revealed that theeslBmutant produced PG with reduced levels ofO-acetylation. Using growth and autolysis assays, we showed that the absence of EslB manifests in a growth defect in media containing high concentrations of sugars and increased endogenous cell lysis. A thinner PG layer produced by theeslBmutant under these growth conditions might explain these phenotypes. Furthermore, theeslBmutant had a noticeable cell division defect and formed elongated cells. Microscopy analysis revealed that an early cell division protein still localized in theeslBmutant, indicating that a downstream process is perturbed. Based on our results, we hypothesize that EslB affects the biosynthesis and modification of the cell wall in L. monocytogenes and is thus important for the maintenance of cell wall integrity.IMPORTANCEThe ABC transporter EslABC is associated with the intrinsic lysozyme resistance of Listeria monocytogenes. However, the exact role of the transporter in this process and in the physiology of L. monocytogenes is unknown. Using different assays to characterize aneslBdeletion strain, we found that the absence of EslB affects not only lysozyme resistance but also endogenous cell lysis, cell wall biosynthesis, cell division, and the ability of the bacterium to grow in media containing high concentrations of sugars. Our results indicate that EslB is, by means of a yet-unknown mechanism, an important determinant for cell wall integrity in L. monocytogenes.