Regulation of the FecI-type ECF sigma factor by transmembrane signalling

Braun, Volkmar; Mahren, Susanne; Ogierman, Monica A.

doi:10.1016/s1369-5274(03)00022-5

Cited by 144 publications

(140 citation statements)

References 23 publications

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“…atu3692 encodes a putative sigma factor that shows the most similarity with sigma factors involved in iron-dependent regulation of siderophore biosynthesis in Pseudomonas spp., including PbrA from P. fluorescens M114 (Venturi et al, 1995), PfrI from P. putida WCS358 (Sexton et al, 1995), and PvdS from P. aeruginosa (Ochsner et al, 1995). Finally, atu3693 encodes a protein with similarity to FecR, also involved in iron-mediated gene regulation (Braun et al, 2003;Ochs et al, 1995). The presence of these genes adjacent to the ATS gene cluster supports our hypothesis that this gene cluster encodes the biosynthesis of a siderophore.…”

Section: Structure Of the Ats Gene Clustersupporting

confidence: 67%

Identification and analysis of a siderophore biosynthetic gene cluster from Agrobacterium tumefaciens C58

2004

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Using the complete genome sequence from Agrobacterium tumefaciens C58, the authors identified a secondary metabolite gene cluster that encodes the biosynthesis of a metabolite with siderophore activity. Support for this conclusion came from genetic and regulatory analysis of the gene cluster, along with the purification of a metabolite from A. tumefaciens C58 with iron-chelating activity. Genetic analysis of mutant strains disrupted in this gene cluster showed that these strains grew more slowly than the wild-type strain in medium lacking iron. Additionally, the mutant strains failed to produce a chrome-azurol-S-reactive material in liquid or solid medium, and failed to produce the metabolite with iron-chelating characteristics that was identified in the wild-type strain. Addition of this purified metabolite to the growth medium of a mutant strain restored its ability to grow in iron-deficient medium. Furthermore, expression of this gene cluster was induced by growth under iron-limiting conditions, suggesting that expression of this gene cluster occurs when iron is scarce. These data are all consistent with the proposal that the proteins encoded by this gene cluster are involved in the production of a siderophore. Interestingly, these proteins show the highest level of amino acid similarity to proteins from a gene cluster found in the filamentous cyanobacterium Nostoc sp. PCC7120, rather than to known siderophore biosynthetic enzymes. Given these properties, it is proposed that the siderophore produced by A. tumefaciens C58 will have a unique chemical structure. Production of the siderophore was not required for virulence of A. tumefaciens when tested with a standard stem inoculation assay.

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Section: Structure Of the Ats Gene Clustersupporting

confidence: 67%

Identification and analysis of a siderophore biosynthetic gene cluster from Agrobacterium tumefaciens C58

2004

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“…Binding of ferric citrate to FecA induces transcription of the ferric citrate transport genes fecABCDE (4,5,7). Transport of ferric citrate is not required for induction.…”

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confidence: 99%

“…FecR interacts with the FecI sigma factor in the cytoplasm and controls transcription initiation of the fec transport genes (18,43). Comparisons with genome sequences of other bacteria reveal homologs of FecIRA whose encoding genes are arranged in the same order as fecIRA of E. coli (7). Particularly abundant are fecIRA homologs in Pseudomonas aeruginosa (46), Pseudomonas putida (34), Nitrosomonas europaea, and Bacteroides thetaiotaomicron, for which 10, 11, 15, and 23 fecIRA gene clusters, respectively, are predicted (V. Braun and S. Mahren, unpublished results).…”

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confidence: 99%

Defined Inactive FecA Derivatives Mutated in Functional Domains of the Outer Membrane Transport and Signaling Protein of Escherichia coli K-12

Sauter

Braun

2004

J Bacteriol

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The FecA outer membrane protein of Escherichia coli functions as a transporter of ferric citrate and as a signal receiver and signal transmitter for transcription initiation of the fec transport genes. Three FecA regions for which functional roles have been predicted from the crystal structures were mutagenized: (i) loops 7 and 8, which move upon binding of ferric citrate and close the entrance to the ferric citrate binding site; (ii) the dinuclear ferric citrate binding site; and (iii) the interface between the globular domain and the ␤-barrel. Deletion of loops 7 and 8 abolished FecA transport and induction activities. Deletion of loops 3 and 11 also inactivated FecA, whereas deletion of loops 9 and 10 largely retained FecA activities. The replacement of arginine residue R365 or R380 and glutamine Q570, which are predicted to serve as binding sites for the negatively charged dinuclear ferric citrate, with alanine resulted in inactive FecA, whereas the binding site mutant R438A retained approximately 50% of the FecA induction and transport activities. Residues R150, E541, and E587, conserved among energy-coupled outer membrane transporters, are predicted to form salt bridges between the globular domain and the ␤-barrel and to contribute to the fixation of the globular domain inside the ␤-barrel. Mutations E541A and E541R affected FecA induction and transport activity slightly, whereas mutations E587A and E587R more strongly reduced FecA activity. The double mutations R150A E541R and R150A E587R nearly abolished FecA activity. Apparently, the salt bridges are less important than the individual functions these residues seem to have for FecA activity. Comparison of the properties of the FecA, FhuA, FepA, and BtuB transporters indicates that although they have very similar crystal structures, the details of their functional mechanisms differ.

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“…The assay was performed in the presence of AMP-PNP instead of ATP to avoid MalK-and MalT-driven ATP hydrolysis, which might interfere with the assay. In addition, given that MalT-dependence on maltotriose is only partial in the presence of AMP-PNP, 3 maltotriose was omitted from the assay. This omission avoided the possibility that maltotriose might impede repression by MalK.…”

Section: Malk Inhibits Transcription Activation By Malt In Vitro-mentioning

confidence: 99%

“…2). In the case of the ferric citrate transport system, substrate binding to the receptor located in the outer membrane triggers the activation of a specific sigma factor via a complex signaling cascade (3). This paper deals with the roles that ATP-binding cassette transporters play in signaling pathways.…”

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confidence: 99%

MalK, the ATP-binding Cassette Component of the Escherichia coli Maltodextrin Transporter, Inhibits the Transcriptional Activator MalT by Antagonizing Inducer Binding

Joly

Böhm

Boos

et al. 2004

Journal of Biological Chemistry

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Regulation of the FecI-type ECF sigma factor by transmembrane signalling

Cited by 144 publications

References 23 publications

Identification and analysis of a siderophore biosynthetic gene cluster from Agrobacterium tumefaciens C58

Identification and analysis of a siderophore biosynthetic gene cluster from Agrobacterium tumefaciens C58

Defined Inactive FecA Derivatives Mutated in Functional Domains of the Outer Membrane Transport and Signaling Protein of Escherichia coli K-12

MalK, the ATP-binding Cassette Component of the Escherichia coli Maltodextrin Transporter, Inhibits the Transcriptional Activator MalT by Antagonizing Inducer Binding

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