Siderophore-mediated iron uptake in Alcaligenes eutrophus CH34 and identification of aleB encoding the ferric iron-alcaligin E receptor

Gilis, Anja; Khan, Muhammad Ayub; Cornélis, Pierre; Meyer, Jean Marie; Mergeay, M.; Lelie, Daniël van der

doi:10.1128/jb.178.18.5499-5507.1996

Cited by 39 publications

(40 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…BLASTP analysis at the P. aeruginosa Genome Project database revealed that PA4675 displays 46 % identity to IutA. An additional putative TonB-dependent receptor, PA1365, displaying 29 % identity to IutA was also identified, although this receptor displays over 50 % identity with the alcaligin E receptor, AleB, from Ralstonia metallidurans (Gilis et al, 1996).…”

Section: Resultsmentioning

confidence: 99%

Identification and characterization of an iron-regulated gene, chtA, required for the utilization of the xenosiderophores aerobactin, rhizobactin 1021 and schizokinen by Pseudomonas aeruginosa

2006

View full text Add to dashboard Cite

Pseudomonas aeruginosa utilizes several xenosiderophores under conditions of iron limitation, including the citrate hydroxamate siderophore aerobactin. Analysis of the P. aeruginosa genome sequence revealed the presence of two genes, chtA (PA4675) and PA1365, encoding proteins displaying significant similarity to the aerobactin outer-membrane receptor, IutA, of Escherichia coli. The chtA and PA1365 genes were mutated by insertional inactivation and it was demonstrated that ChtA is the outer-membrane receptor for aerobactin. ChtA also mediated the utilization of rhizobactin 1021 and schizokinen, which are structurally similar to aerobactin. In contrast to the utilization of other xenosiderophores by P. aeruginosa, there was no apparent redundancy in the utilization of aerobactin, rhizobactin 1021 and schizokinen. The utilization of citrate hydroxamate siderophores by P. aeruginosa was demonstrated to be TonB1 dependent. A Fur box was identified in the region directly upstream of chtA and it was demonstrated by the in vivo Fur titration assay that this region is capable of binding Fur and accordingly that expression of chtA is iron regulated. The PA1365 mutant was unaffected in the utilization of citrate hydroxamate siderophores. INTRODUCTIONWith few exceptions, all organisms display an absolute nutritional requirement for iron. For pathogenic bacteria, the host environment may be considered an iron-depleted environment, with all available iron located intracellularly or bound by high-affinity iron-binding proteins such as transferrin and lactoferrin (Litwin & Calderwood, 1993;Payne, 1993;Crosa, 1997). Under conditions of iron limitation, many bacteria produce low-molecular-mass highaffinity chelators termed siderophores that bind ferric iron and deliver it to the cell via specific outer-membrane receptors. Additionally, many bacterial pathogens also encode specific transport systems that allow for the assimilation of iron from host proteins such as haemoglobin, transferrin and lactoferrin (Ratledge & Dover, 2000;Genco & Dixon, 2001).Pseudomonas aeruginosa is an opportunistic human pathogen that causes severe and often fatal infections and is the predominant cause of respiratory infections in individuals with cystic fibrosis. P. aeruginosa synthesizes two known siderophores, pyoverdine (Cox & Adams, 1985) and pyochelin (Cox, 1980), and has also been shown to be capable of utilizing a variety of xenosiderophores including enterobactin (Poole et al., 1990) and desferrioxamine mesylate (Meyer, 1992). The ability of P. aeruginosa to utilize a wide variety of xenosiderophores possibly allows it to compete effectively with other micro-organisms for available iron and consequently to occupy extended ecological niches. However, despite the variety of xenosiderophores known to be transported by P. aeruginosa, in many cases their cognate outer-membrane receptors have not been identified.Siderophore receptors function as gated channels in the outer membrane and display relatively tight specificity for their cognate sideropho...

show abstract

Section: Resultsmentioning

confidence: 99%

Identification and characterization of an iron-regulated gene, chtA, required for the utilization of the xenosiderophores aerobactin, rhizobactin 1021 and schizokinen by Pseudomonas aeruginosa

2006

View full text Add to dashboard Cite

show abstract

“…For a number of reasons, we strongly believe that this CAS-reactive substance represents a bona fide siderophore. First, the CAS assay has reliably identified and characterized a range of siderophores encompassing the iron chelators of over 20 bacterial genera (2,3,5,12,18,20,21,27,33,36,37,38,47,48,51,58,66,68,74,80,82,85,98). Second, the presence of CAS-reactive material correlated with enhanced aerobic growth in an iron-depleted defined medium (68).…”

Section: Discussionmentioning

confidence: 99%

“…This list has grown appreciably in recent years, largely due to the availability of the CAS assay. There are a number of other bacterial siderophores that, like legiobactin, do not possess the classic catecholate or hydroxamate structure and thus were or would have been overlooked by the Arnow and Csáky assays (12,15,18,33,37,61,68,85,94). In some ways, it is not surprising that L. pneumophila produces a siderophore.…”

Section: Discussionmentioning

confidence: 99%

Discovery of a Nonclassical Siderophore, Legiobactin, Produced by Strains ofLegionella pneumophila

2000

View full text Add to dashboard Cite

The mechanisms by which Legionella pneumophila, a facultative intracellular parasite and the agent of Legionnaires' disease, acquires iron are largely unexplained. Several earlier studies indicated that L. pneumophila does not elaborate siderophores. However, we now present evidence that supernatants from L. pneumophila cultures can contain a nonproteinaceous, high-affinity iron chelator. More specifically, when aerobically grown in a low-iron, chemically defined medium (CDM), L. pneumophila secretes a substance that is reactive in the chrome azurol S (CAS) assay. Importantly, the siderophore-like activity was only observed when the CDM cultures were inoculated to relatively high density with bacteria that had been grown overnight to log or early stationary phase in CDM or buffered yeast extract. Inocula derived from late-stationary-phase cultures, despite ultimately growing, consistently failed to result in the elaboration of siderophore-like activity. The Legionella CAS reactivity was detected in the culture supernatants of the serogroup 1 strains 130b and Philadelphia-1, as well as those from representatives of other serogroups and other Legionella species. The CAS-reactive substance was resistant to boiling and protease treatment and was associated with the <1-kDa supernatant fraction. As would also be expected for a siderophore, the addition of 0.5 or 2.0 M iron to the cultures repressed the expression of the CAS-reactive substance. Interestingly, the supernatants were negative in the Arnow, Csáky, and Rioux assays, indicating that the Legionella siderophore was not a classic catecholate or hydroxamate and, hence, might have a novel structure. We have designated the L. pneumophila siderophore legiobactin.The bacterium Legionella pneumophila is a ubiquitous inhabitant of natural and man-made aquatic environments, surviving both free, in biofilms, and as an intracellular parasite of protozoa (1,8,26,49,50). Yet, this gram-negative microbe is best known for being the principal etiologic agent of Legionnaires' disease, a potentially fatal form of human pneumonia (59,95). Within the lung, L. pneumophila flourishes as an intracellular parasite of the alveolar macrophages and perhaps the epithelium (1,8,13,41,63,84). A variety of studies indicate that iron is a key requirement for L. pneumophila extracellular replication, intracellular infection, and virulence (7,9,10,25,31,39,40,44,45,60,65,71,72,76,77,78,86,89,91). Despite this, the molecular basis of Legionella iron acquisition, particularly its earliest stages, is relatively unclear.Among all of the considerations regarding Legionella iron acquisition, it is the issue of siderophore production by L. pneumophila that has been the most controversial. In the early 1980s, shortly after the discovery of the Legionella genus, it was reported that L. pneumophila does not produce siderophores (79). This conclusion was based upon the negative results that were obtained from a standard bioassay, as well as the Arnow and Csáky assays, the customary methods for detecting ...

show abstract

“…Figure 1 depicts the possible locations of the products of these genes in cells, as predicted from the locations of their homologues. Sll1406, Sll1409, Slr1490, and Sll1206 are homologous to FhuA of E. coli (7) and IutA of Alcaligenes eutrophus (10), which are located in the outer membrane. Sll1202, Slr1491, Slr1492, and Slr1319 showed similarities with FhuD and FecB of E. coli (7,22).…”

Section: Location Of Gene Products and Genes Inactivated In The Mutantsmentioning

confidence: 99%

Genes Essential to Iron Transport in the Cyanobacterium Synechocystis sp. Strain PCC 6803

et al. 2001

View full text Add to dashboard Cite

Genes encoding polypeptides of an ATP binding cassette (ABC)-type ferric iron transporter that plays a major role in iron acquisition in Synechocystis sp. strain PCC 6803 were identified. These genes are slr1295, slr0513, slr0327, and recently reported sll1878 (Katoh et al., J. Bacteriol. 182:6523-6524, 2000) and were designated futA1, futA2, futB, and futC, respectively, for their involvement in ferric iron uptake. Inactivation of these genes individually or futA1 and futA2 together greatly reduced the activity of ferric iron uptake in cells grown in complete medium or iron-deprived medium. All the fut genes are expressed in cells grown in complete medium, and expression was enhanced by iron starvation. The futA1 and futA2 genes appear to encode periplasmic proteins that play a redundant role in iron binding. The deduced products of futB and futC genes contain nucleotide-binding motifs and belong to the ABC transporter family of inner-membrane-bound and membrane-associated proteins, respectively. These results and sequence similarities among the four genes suggest that the Fut system is related to the Sfu/Fbp family of iron transporters. Inactivation of slr1392, a homologue of feoB in Escherichia coli, greatly reduced the activity of ferrous iron transport. This system is induced by intracellular low iron concentrations that are achieved in cells exposed to iron-free medium or in the fut-less mutants grown in complete medium.

show abstract

Siderophore-mediated iron uptake in Alcaligenes eutrophus CH34 and identification of aleB encoding the ferric iron-alcaligin E receptor

Cited by 39 publications

References 59 publications

Identification and characterization of an iron-regulated gene, chtA, required for the utilization of the xenosiderophores aerobactin, rhizobactin 1021 and schizokinen by Pseudomonas aeruginosa

Identification and characterization of an iron-regulated gene, chtA, required for the utilization of the xenosiderophores aerobactin, rhizobactin 1021 and schizokinen by Pseudomonas aeruginosa

Discovery of a Nonclassical Siderophore, Legiobactin, Produced by Strains ofLegionella pneumophila

Genes Essential to Iron Transport in the Cyanobacterium Synechocystis sp. Strain PCC 6803

Contact Info

Product

Resources

About