Catechol Siderophore Transport by Vibrio cholerae

Area of Science:

• Microbiology
• Molecular Biology
• Pathogen Biology

Background:

• Vibrio cholerae, a significant human pathogen, requires iron for survival and pathogenesis.
• V. cholerae synthesizes its own siderophore, vibriobactin, but also utilizes siderophores from other bacteria, like Escherichia coli's enterobactin.
• Understanding siderophore utilization is crucial for comprehending V. cholerae's persistence and nutrient acquisition strategies.

Purpose of the Study:

• To investigate V. cholerae's capacity to acquire iron using heterologous siderophores.
• To clarify V. cholerae's interaction with enterobactin, specifically distinguishing between cyclic and linear forms.
• To identify the specific receptors and TonB systems involved in catechol siderophore transport and iron acquisition.

Main Methods:

• Transport assays were conducted using V. cholerae strains lacking specific siderophore receptors or esterases.
• The functionality of siderophore receptors (IrgA, VctA, ViuA) was assessed using various siderophores, including enterobactin derivatives and MECAM.
• The role of ViuB, a putative siderophore-interacting protein, in iron release was examined by comparing siderophore utilization in wild-type and mutant strains.

Main Results:

• V. cholerae does not transport cyclic enterobactin but efficiently utilizes its linear derivatives.
• Linear enterobactin derivatives are transported by V. cholerae via the IrgA and VctA receptors.
• Vibriobactin is transported by ViuA, while fluvibactin is transported by IrgA, VctA, and ViuA; ViuB is essential for vibriobactin utilization but not for others, suggesting an additional ferric reductase.

Conclusions:

• V. cholerae's iron acquisition strategy involves the specific uptake of linear enterobactin derivatives through IrgA and VctA.
• The pathogen possesses multiple catechol siderophore receptors, enabling the utilization of a diverse range of iron-scavenging molecules.
• The requirement of ViuB for some siderophores but not others indicates the presence of an uncharacterized ferric reductase in V. cholerae for iron release.