Listeria monocytogenes is a Gram‐positive, intracellular pathogen harboring the surface‐associated virulence factor InlB, which enables entry into certain host cells. Structurally diverse wall teichoic acids (WTAs), which can also be differentially glycosylated, determine the antigenic basis of the various Listeria serovars. WTAs have many physiological functions; they can serve as receptors for bacteriophages, and provide a substrate for binding of surface proteins such as InlB. In contrast, the membrane‐anchored lipoteichoic acids (LTAs) do not show significant variation and do not contribute to serovar determination. It was previously demonstrated that surface‐associated InlB non‐covalently adheres to both WTA and LTA, mediating its retention on the cell wall. Here, we demonstrate that in a highly virulent serovar 4b strain, two genes gtlB and gttB are responsible for galactosylation of LTA and WTA respectively. We evaluated the InlB surface retention in mutants lacking each of these two genes, and found that only galactosylated WTA is required for InlB surface presentation and function, cellular invasiveness and phage adsorption, while galactosylated LTA plays no role thereof. Our findings demonstrate that a simple pathogen‐defining serovar antigen, that mediates bacteriophage susceptibility, is necessary and sufficient to sustain the function of an important virulence factor.

中文翻译：

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半乳糖基化壁磷壁酸，但不是脂磷壁酸，在血清型 4b 单核细胞增生李斯特菌表面保留 InlB

单核细胞增生李斯特菌是一种革兰氏阳性细胞内病原体，具有表面相关的毒力因子 InlB，可以进入某些宿主细胞。结构多样的壁磷壁酸 (WTA)，也可以被差异糖基化，决定了各种李斯特菌的抗原基础血清型。WTA具有许多生理功能；它们可以作为噬菌体的受体，并为结合表面蛋白（如 InlB）提供底物。相比之下，膜锚定的脂磷壁酸 (LTA) 没有显示出显着的变化，并且对血清型测定没有贡献。先前已经证明，表面相关的 InlB 非共价地粘附在 WTA 和 LTA 上，介导其在细胞壁上的保留。在这里，我们证明在一个高毒力血清型 4b 菌株中，两个基因gtlB和gttB分别负责 LTA 和 WTA 的半乳糖基化。我们评估了缺乏这两个基因的突变体中的 InlB 表面保留，并发现 InlB 表面呈现和功能、细胞侵袭性和噬菌体吸附只需要半乳糖基化 WTA，而半乳糖基化 LTA 则不起作用。我们的研究结果表明，介导噬菌体易感性的简单病原体定义血清型抗原对于维持重要毒力因子的功能是必要且足够的。