Glycocluster Tetrahydroxamic Acids Exhibiting Unprecedented Inhibition of Pseudomonas aeruginosa Biofilms

Opportunistic Gram-negative Pseudomonas aeruginosa uses adhesins (e.g., LecA and LecB lectins, type VI pili and flagella) and iron to invade host cells with the formation of a biofilm, a thick barrier that protects bacteria from drugs and host immune system. Hindering iron uptake and disrupting adhesins’ function could be a relevant antipseudomonal strategy. To test this hypothesis, we designed an iron-chelating glycocluster incorporating a tetrahydroxamic acid and α-l-fucose bearing linker to interfere with both iron uptake and the glycan recognition process involving the LecB lectin. Iron depletion led to increased production of the siderophore pyoverdine by P. aeruginosa to counteract the loss of iron uptake, and strong biofilm inhibition was observed not only with the α-l-fucocluster (72%), but also with its α-d-manno (84%), and α-d-gluco (92%) counterparts used as negative controls. This unprecedented finding suggests that both LecB and biofilm inhibition are closely related to the presence of hydroxamic acid groups.机会性革兰氏阴性铜绿假单胞菌（Pseudomonas aeruginosa）可通过黏附素（如凝集素LecA、LecB、VI型菌毛及鞭毛）与铁离子侵袭宿主细胞，并形成生物被膜——这一厚实屏障可保护细菌抵御药物与宿主免疫系统的攻击。阻碍铁摄取并破坏黏附素功能，或是一种颇具应用前景的抗铜绿假单胞菌治疗策略。为验证这一假说，我们设计了一款整合四羟肟酸与带有α-L-岩藻糖连接臂的铁螯合糖簇，以期同时干扰铁摄取过程与涉及LecB凝集素的糖识别通路。实验发现，铜绿假单胞菌会通过增加铁载体绿脓杆菌素（pyoverdine）的合成以代偿铁摄取受阻的影响；且不仅α-L-岩藻糖簇（生物被膜抑制率72%）可显著抑制生物被膜形成，作为阴性对照的α-D-甘露糖簇（抑制率84%）与α-D-葡萄糖簇（抑制率92%）同样展现出较强的抑制效果。这一前所未有的研究结果表明，LecB凝集素功能与生物被膜形成的抑制均与羟肟酸基团的存在密切相关。