AbstractCeramidases (CDases) are important in controlling skin barrier integrity by regulating ceramide composition and affording downstream signal molecules. While the functions of epidermal CDases are known, roles of neutral CDases secreted by skin‐residing microbes are undefined. Here, we developed a one‐step fluorogenic substrate, S‐B, for specific detection of bacterial CDase activity and inhibitor screening. We identified a non‐hydrolyzable substrate mimic, C6, as the best hit. Based on C6, we designed a photoaffinity probe, JX‐1, which efficiently detects bacterial CDases. Using JX‐1, we identified endogenous low‐abundance PaCDase in a P. aeruginosa monoculture and in a mixed skin bacteria culture. Harnessing both S‐B and JX‐1, we found that CDase activity positively correlates with the relative abundance of P. aeruginosa and is negatively associated with wound area reduction in clinical diabetic foot ulcer patient samples. Overall, our study demonstrates that bacterial CDases are important regulators of skin ceramides and potentially play a role in wound healing.
摘要神经酰胺酶(CD酶)通过调节神经酰胺的组成和提供下游信号分子,在控制皮肤屏障完整性方面发挥着重要作用。虽然表皮 CD 酶的功能已为人所知,但皮肤寄居微生物分泌的中性 CD 酶的作用尚未明确。在此,我们开发了一种一步法荧光底物 S-B,用于特异性检测细菌 CD 酶活性和筛选抑制剂。我们发现了一种不可水解的底物模拟物--C6,它是最佳命中物。在 C6 的基础上,我们设计了一种光亲和探针 JX-1,它能有效地检测细菌 CD 酶。利用 JX-1,我们在铜绿假单胞菌和混合皮肤细菌培养物中鉴定出了内源性低丰度 PaCDase。利用 S-B 和 JX-1,我们发现在临床糖尿病足溃疡患者样本中,CD 酶活性与铜绿假单胞菌的相对丰度呈正相关,与伤口面积缩小呈负相关。总之,我们的研究表明,细菌 CD 酶是皮肤神经酰胺的重要调节剂,可能在伤口愈合中发挥作用。