The csbX gene of Azotobacter vinelandii encodes an MFS efflux pump required for catecholate siderophore export

摘要

The csbX gene of Azotobacter vinelandii was regulated in an iron-repressible manner from a divergent promoter upstream of the catecholate siderophore biosynthesis (csb) operon and was predicted to encode an efflux pump of the major facilitator superfamily. Other proteins that were most similar to CsbX were encoded by genes found in the catecholate siderophore biosynthesis operons of Aeromonas hydrophila and Stigmatella aurantiaca. Inactivation of csbX resulted in 57-100% decrease in the amount of catecholates released when compared to the wild-type in iron-limited medium. CsbX was most important for the export of the high affinity chelator protochelin with the majority of the catecholates released by esbX mutants being the protochelin intermediates azotochelin and aminochelin. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved. [References: 31]