Siderophores uptake pathway

FIGURE 7.8 A representation of the siderophore uptake pathway in . co/i using ferric-enterobactin (FeEnt) transport as an example (see text for details). (From Chu et al, 2010. Reproduced with permission from Springer.)... 

Soft rot spreading depends on the efficiency of the iron uptake pathway mediated by the siderophore chrysobactin. Biosynthesis of the ferrichrysobactin outer membrane receptor (Fct) and of the chrysobactin precursor, i.e. the activated form of 2,3-dihydroxybenzoic acid, are encoded by an operon,/cr ebsCEBA [3]. 

The mutant L37 cbrA21 is affected as regards to its iron uptake pathway mediated by the siderophore achromobactin. Because this mutation results in derepression of the chrysobactin mediated iron transport pathway, the mutant is probably less susceptible to iron deprivation than wild-type cells are, when entering the host. This results in a delay in Pels production thus leading to delayed symptoms, as reported by Sauvage and Expert (1994). 

Iron uptake from transferrin, siderophores, and haem by Gram-negative bacteria is represented schematically in Fig. 7.5. AU three iron uptake pathways require an outer-membrane receptor, a periplasmic-binding protein (PBP), and an inner-membrane ATP-binding cassette (ABC) transporter. Whereas Fe " -siderophores and haem... 

Combining fluorescence spectroscopy with fluorescence microscopy, confocal microscopy could be used to elucidate the pathway of siderophore-mediat iron uptake in the fungus Ustilago maydis, and visualize this pathway by providing unique fluorescent microscopic images. Using these techniques, clear images of two independent iron-uptake mechanisms have become visualized as well as their cellular compartment locahzed. 

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