Chemical synthesis and biological evaluation of gallidermin-siderophore conjugates
作者:Sabesan Yoganathan、Clarissa S. Sit、John C. Vederas
DOI:10.1039/c0ob00846j
日期:——
The lantibiotic gallidermin was modified at lysine residues by regioselective attachment of derivatives of pyochelin, agrobactin and desferrioxamine B with the objective of having siderophore receptors of Gram-negative bacteria transport the antibiotic-iron chelator conjugate through the outer membrane. All of the conjugates retained activity against the Gram-positive indicator strain, Lactococcus lactis subsp. cremorisHP. However, testing of the conjugates against several Gram-negative strains yielded unexpected results. Bacteria treated with 100 μM of the conjugates complexed with Fe3+ grew better than bacteria grown in iron-free media but worse than bacteria grown in the same media supplemented with 10 μM FeCl3. Although these findings indicate that the conjugates are unable to inhibit the growth of Gram-negative bacteria, they indicate penetration of the outer membrane and provide structure–activity information for design of other lantibiotic conjugates. The synthetic strategy is applicable for linking biomarkers or fluorescence probes to gallidermin for studies on its localization and mode of action. As there are many lantibiotics that operate with unknown mechanisms of action, this chemical approach provides a means to modify such peptides with biomarkers for biological investigations.
氨基酸肽素(lantibiotic)伽利德明(gallidermin)通过区域选择性地连接派克霉素(pyochelin)、农杆菌素(agrobactin)和去铁氧胺B(desferrioxamine B)的衍生物,修改了赖氨酸残基,旨在利用革兰阴性细菌的侧铁素受体将抗生素-铁螯合剂结合物运输通过外膜。所有的结合物对革兰阳性指示菌Lactococcus lactis subsp. cremorisHP保持活性。然而,对几种革兰阴性菌株的测试结果出乎意料。用100 μM的结合物与Fe3+复合处理的细菌其生长情况优于在无铁培养基中生长的细菌,但低于在添加10 μM FeCl3的同一培养基中生长的细菌。尽管这些发现表明结合物无法抑制革兰阴性细菌的生长,但它们显示了外膜的穿透能力,并为其他氨基酸肽素结合物的设计提供了结构-活性信息。这种合成策略可用于将生物标志物或荧光探针连接到伽利德明上,以研究其定位和作用机制。由于许多氨基酸肽素的作用机制尚不明确,这种化学方法为改造此类肽以进行生物研究提供了一种途径。