Lamont Iain L, Beare Paul A, Ochsner Urs, Vasil Adriana I, Vasil Michael L
Department of Biochemistry and Centre for Gene Research, University of Otago, P.O. Box 56, Dunedin, New Zealand.
Proc Natl Acad Sci U S A. 2002 May 14;99(10):7072-7. doi: 10.1073/pnas.092016999. Epub 2002 May 7.
Numerous bacteria secrete low molecular weight compounds termed siderophores that have a high affinity for iron ions. Siderophores have a well-documented role as iron-scavenging chemicals, chelating iron ions in the environment whereupon the ferrisiderophores reenter the bacterial cells by means of specific cell-surface receptors. The iron is then released for incorporation into bacterial proteins. Here we show that in addition to its role as an iron-scavenger, the siderophore pyoverdine that is secreted by Pseudomonas aeruginosa regulates the production of at least three virulence factors (exotoxin A, an endoprotease, and pyoverdine itself), which are major contributors to the ability of this bacterium to cause disease. Regulation occurs through a transmembrane signaling system that includes an outer membrane receptor for ferripyoverdine, a signal-transducing protein that is predicted to extend from the periplasm into the cytoplasm, and a sigma factor. Expression of genes that form part of the regulon is triggered by pyoverdine so that this siderophore acts as a signaling molecule to control the production of secreted products. Recognition that a siderophore acts as a signaling molecule has important implications for the understanding of interactions between bacterial cells.
许多细菌会分泌被称为铁载体的低分子量化合物，这些化合物对铁离子具有很高的亲和力。铁载体作为铁清除化学物质的作用已得到充分证明，它们在环境中螯合铁离子，然后铁-铁载体通过特定的细胞表面受体重新进入细菌细胞。随后铁被释放出来用于掺入细菌蛋白质中。我们在此表明，除了作为铁清除剂的作用外，铜绿假单胞菌分泌的铁载体绿脓菌素还调节至少三种毒力因子（外毒素A、一种内蛋白酶和绿脓菌素本身）的产生，这些毒力因子是该细菌致病能力的主要贡献因素。调节通过一个跨膜信号系统发生，该系统包括铁-绿脓菌素的外膜受体、一种预计从周质延伸到细胞质的信号转导蛋白和一个σ因子。构成调节子一部分的基因的表达由绿脓菌素触发，因此这种铁载体作为一种信号分子来控制分泌产物的产生。认识到铁载体作为信号分子具有重要意义，有助于理解细菌细胞之间的相互作用。
