The National Research Laboratory of Defense Proteins, College of Pharmacy, Pusan National University, Busan, Republic of Korea.
Dev Comp Immunol. 2011 Aug;35(8):835-9. doi: 10.1016/j.dci.2011.03.001. Epub 2011 Mar 29.
We recently reported that D-alanylation of Staphylococcus aureus wall teichoic acid (WTA) mitigates an induction of the Toll-mediated humoral response in Drosophila by interfering with peptidoglycan (PG) recognition by PG recognition protein-SA (PGRP-SA). Here, we investigated the mode of this interference by using an in vitro cell free system from larvae of the coleoptran insect Tenebrio molitor. WTA modification on PG had a potent inhibitory effect on PGRP-SA-mediated Toll proteolytic cascade activation, and the D-alanylation of WTA enhanced its inhibitory effect. Purified D-alanylated WTA released from PG lost its inhibitory action on both Toll cascade activation and PGRP-SA binding to insoluble PG. The inhibition of PGRP-SA binding to PG by D-alanylated WTA took place not only on polymeric PG but also on WTA-attached disaccharide units of monomeric PG. These results suggest that D-alanylation-mediated evasion requires the covalent bonding of D-alanylated WTA to PG, but not net-like cross-linking structure of PG.
我们最近报道称，金黄色葡萄球菌壁磷壁酸（WTA）的 D-丙氨酸化通过干扰肽聚糖（PG）识别蛋白-SA（PGRP-SA）来减轻果蝇 Toll 介导的体液反应的诱导。在这里，我们使用来自鞘翅目昆虫 T. molitor 幼虫的体外无细胞系统研究了这种干扰的模式。PG 上的 WTA 修饰对 PGRP-SA 介导的 Toll 蛋白水解级联激活具有强烈的抑制作用，而 WTA 的 D-丙氨酸化增强了其抑制作用。从 PG 释放的纯化 D-丙氨酸化 WTA 丧失了对 Toll 级联激活和 PGRP-SA 与不溶性 PG 结合的抑制作用。D-丙氨酸化 WTA 对 PGRP-SA 与 PG 结合的抑制作用不仅发生在聚合 PG 上，也发生在单体 PG 上 WTA 连接的二糖单元上。这些结果表明，D-丙氨酸化介导的逃逸需要 D-丙氨酸化 WTA 与 PG 的共价结合，而不是 PG 的网状交联结构。
