PDF(Pubmed)
Abstract：
One of the mechanisms employed by the opportunistic pathogen Burkholderia cenocepacia to acquire the essential element iron is the production and release of two ferric iron chelating compounds (siderophores), ornibactin and pyochelin. Here we show that B. cenocepacia is also able to take advantage of a range of siderophores produced by other bacteria and fungi (\'xenosiderophores\') that chelate iron exclusively by means of hydroxamate groups. These include the tris-hydroxamate siderophores ferrioxamine B, ferrichrome, ferricrocin and triacetylfusarinine C, the bis-hydroxamates alcaligin and rhodotorulic acid, and the monohydroxamate siderophore cepabactin. We also show that of the 24 TonB-dependent transporters encoded by the B. cenocepacia genome, two (FhuA and FeuA) are involved in the uptake of hydroxamate xenosiderophores, with FhuA serving as the exclusive transporter of iron-loaded ferrioxamine B, triacetylfusarinine C, alcaligin and rhodotorulic acid, while both FhuA and FeuA are able to translocate ferrichrome-type siderophores across the outer membrane. Finally, we identified FhuB, a putative cytoplasmic membrane-anchored ferric-siderophore reductase, as being obligatory for utilization of all of the tested bis- and tris-hydroxamate xenosiderophores apart from alcaligin.
摘要：
机会病原体伯克霍尔德氏菌获得必需元素铁的机制之一是产生和释放两种三价铁螯合化合物（铁载体），ornibactin和pyochelin。在这里，我们表明，隐球菌也能够利用由其他细菌和真菌产生的一系列铁载体（“异型铁载体”），这些铁载体仅通过异羟肟酸盐基团螯合铁。这些包括三-异羟肟酸铁载体铁三嗪B，ferrichrome,铁黄霉素和三乙酰镰刀碱C，双异羟肟酸盐赤霉素和罗得托酸，和单羟肟酸类铁载体头孢霉素。我们还表明，在由隐血芽孢杆菌基因组编码的24个TonB依赖性转运蛋白中，两个（FhuA和FeuA）参与异羟肟酸盐异铁载体的摄取，FhuA作为载铁铁胺B的独家转运蛋白，三乙酰镰刀碱C,alcaligin和rhodorulic酸，而FhuA和FeuA都能够在外膜上转移ferrichrome型铁载体。最后,我们确认了FhuB,一种推定的细胞质膜锚定铁-铁载体还原酶，除alcaligin外，必须使用所有测试的双和三羟肟酸盐异铁载体。
