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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EslB是单核细胞增多性李斯特菌细胞壁生物合成和修饰所必需的。
DOI：
10.1128/jb.00553-20
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发表时间：
2021-01-25
影响因子：
3.2
通讯作者：
Gründling A
中科院分区：
文献类型：
--
作者：
Rismondo J;Schulz LM;Yacoub M;Wadhawan A;Hoppert M;Dionne MS;Gründling A
ABC转运蛋白EslABC与单核细胞增多性李斯特菌对溶菌酶的内在耐药有关。然而，转运蛋白在这一过程中的确切作用以及在单核细胞增多性李斯特菌的生理学中的作用尚不清楚。溶菌酶是天然免疫系统的重要组成部分。它的作用是分解细菌的肽聚糖(PG)层。人类病原体单核细胞增多性李斯特菌对溶菌酶具有内在的抗药性。肽聚糖N-脱乙酰基酶PgdA和O-乙酰转移酶OATA是引起其溶菌酶抗性的两个已知因素。此外，研究表明，缺少ABC转运体的成分，在这里称为EslABC，导致溶菌酶抗性降低。它的活性如何与溶菌酶抗性有关尚不清楚。为了进一步研究这一点，在单核细胞增多性乳杆菌菌株10403S中构建了编码ABC转运蛋白的膜成分的eslB缺失的菌株。EslB突变体显示出溶菌酶的最低抑菌浓度降低了40倍。对PG结构的分析表明，eslB突变体产生的PG的O-乙酰化水平降低。通过生长和自溶试验，我们发现EslB的缺失表现为在含有高浓度糖的培养液中的生长缺陷和内源细胞裂解增加。EslB突变体在这些生长条件下产生的较薄的PG层可能解释了这些表型。此外，eslB突变体具有明显的细胞分裂缺陷，并形成细长的细胞。显微镜分析显示，eslB突变体中仍有一个早期细胞分裂蛋白，这表明下游过程受到干扰。根据我们的结果，我们推测EslB影响单核细胞增多性乳杆菌细胞壁的生物合成和修饰，因此对于维持细胞壁的完整性是重要的。ABC转运蛋白EslABC与单核细胞增多性李斯特菌对溶菌酶的内在耐药有关。然而，转运蛋白在这一过程中的确切作用以及在单核细胞增多性李斯特菌的生理学中的作用尚不清楚。使用不同的方法对eslB缺失菌株进行鉴定，我们发现eslB的缺失不仅影响溶菌酶的抗性，而且影响内源细胞裂解、细胞壁生物合成、细胞分裂以及细菌在高浓度糖的培养基中生长的能力。我们的结果表明，EslB通过一种未知的机制，是单核细胞增多性乳杆菌细胞壁完整性的重要决定因素。
The 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. 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 peptidoglycan N-deacetylase PgdA and O-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 in eslB, coding for a membrane component of the ABC transporter, was constructed in L. monocytogenes strain 10403S. The eslB mutant showed a 40-fold reduction in the MIC to lysozyme. Analysis of the PG structure revealed that the eslB mutant produced PG with reduced levels of O-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 the eslB mutant under these growth conditions might explain these phenotypes. Furthermore, the eslB mutant had a noticeable cell division defect and formed elongated cells. Microscopy analysis revealed that an early cell division protein still localized in the eslB mutant, 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. IMPORTANCE The 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 an eslB deletion 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.