This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ó Cuív, P. Articles by O'Connell, M. Search for Related Content PubMed PubMed Citation Articles by Ó Cuív, P. Articles by O'Connell, M.

Identification of rhtX and fptX, Novel Genes Encoding Proteins That Show Homology and Function in the Utilization of the Siderophores Rhizobactin 1021 by Sinorhizobium meliloti and Pyochelin by Pseudomonas aeruginosa, Respectively

School of Biotechnology, Dublin City University, Dublin 9, Ireland

Received 9 December 2003/ Accepted 14 January 2004

Rhizobactin 1021 is a hydroxymate siderophore produced by the soil bacterium Sinorhizobium meliloti 2011. A regulon comprising rhtA, encoding the outer membrane receptor protein for the ferrisiderophore; the biosynthesis operon rhbABCDEF; and rhrA, the Ara-C-like regulator of the receptor and biosynthesis genes has been previously described. We report the discovery of a gene, located upstream of rhbA and named rhtX (for "rhizobactin transport"), which is required, in addition to rhtA, to confer the ability to utilize rhizobactin 1021 on a strain of S. meliloti that does not naturally utilize the siderophore. Rhizobactin 1021 is structurally similar to aerobactin, which is transported in Escherichia coli via the IutA outer membrane receptor and the FhuCDB inner membrane transport system. E. coli expressing iutA and fhuCDB was found to also transport rhizobactin 1021. We demonstrated that RhtX alone could substitute for FhuCDB to transport rhizobactin 1021 in E. coli. RhtX shows similarity to a number of uncharacterized proteins which are encoded proximal to genes that are either known to be or predicted to be involved in iron acquisition. Among these is PA4218 of Pseudomonas aeruginosa, which is located close to the gene cluster that functions in pyochelin biosynthesis and outer membrane transport. PA4218 was mutated by allelic replacement, and the mutant was found to have a pyochelin utilization-defective phenotype. It is proposed that PA4218 be named fptX (for "ferripyochelin transport"). RhtX and FptX appear to be members of a novel family of permeases that function as single-subunit transporters of siderophores.

This article has been cited by other articles:

• Youard, Z. A., Mislin, G. L. A., Majcherczyk, P. A., Schalk, I. J., Reimmann, C. (2007). Pseudomonas fluorescens CHA0 Produces Enantio-pyochelin, the Optical Antipode of the Pseudomonas aeruginosa Siderophore Pyochelin. J. Biol. Chem. 282: 35546-35553 [Abstract] [Full Text]  
• Forman, S., Nagiec, M. J., Abney, J., Perry, R. D., Fetherston, J. D. (2007). Analysis of the aerobactin and ferric hydroxamate uptake systems of Yersinia pestis. Microbiology 153: 2332-2341 [Abstract] [Full Text]  
• Michel, L., Bachelard, A., Reimmann, C. (2007). Ferripyochelin uptake genes are involved in pyochelin-mediated signalling in Pseudomonas aeruginosa. Microbiology 153: 1508-1518 [Abstract] [Full Text]  
• O Cuiv, P., Keogh, D., Clarke, P., O'Connell, M. (2007). FoxB of Pseudomonas aeruginosa Functions in the Utilization of the Xenosiderophores Ferrichrome, Ferrioxamine B, and Schizokinen: Evidence for Transport Redundancy at the Inner Membrane. J. Bacteriol. 189: 284-287 [Abstract] [Full Text]  
• Cowie, A., Cheng, J., Sibley, C. D., Fong, Y., Zaheer, R., Patten, C. L., Morton, R. M., Golding, G. B., Finan, T. M. (2006). An Integrated Approach to Functional Genomics: Construction of a Novel Reporter Gene Fusion Library for Sinorhizobium meliloti. Appl. Environ. Microbiol. 72: 7156-7167 [Abstract] [Full Text]  
• Leach, L. H., Lewis, T. A. (2006). Identification and characterization of Pseudomonas membrane transporters necessary for utilization of the siderophore pyridine-2,6-bis(thiocarboxylic acid) (PDTC).. Microbiology 152: 3157-3166 [Abstract] [Full Text]  
• Cuiv, P. O, Clarke, P., O'Connell, M. (2006). Identification and characterization of an iron-regulated gene, chtA, required for the utilization of the xenosiderophores aerobactin, rhizobactin 1021 and schizokinen by Pseudomonas aeruginosa.. Microbiology 152: 945-954 [Abstract] [Full Text]  
• Chao, T.-C., Buhrmester, J., Hansmeier, N., Puhler, A., Weidner, S. (2005). Role of the Regulatory Gene rirA in the Transcriptional Response of Sinorhizobium meliloti to Iron Limitation. Appl. Environ. Microbiol. 71: 5969-5982 [Abstract] [Full Text]  
• Brickman, T. J., Armstrong, S. K. (2005). Bordetella AlcS Transporter Functions in Alcaligin Siderophore Export and Is Central to Inducer Sensing in Positive Regulation of Alcaligin System Gene Expression. J. Bacteriol. 187: 3650-3661 [Abstract] [Full Text]