The Overlapping
 angB
 and
 angG
 Genes Are Encoded within the
 trans
 -Acting Factor Region of the Virulence Plasmid in
 Vibrio anguillarum
 : Essential Role in Siderophore Biosynthesis

Welch, Timothy J.; Chai, Sunghee; Crosa, Jorge H.

doi:10.1128/jb.182.23.6762-6773.2000

Cited by 41 publications

(67 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Genetic complementation assays and siderophore utilization tests proved that the A. baumannii dhbA, dhbB and dhbE genes encode active proteins that restore enterobactin biosynthesis and iron uptake proficiency when introduced in E. coli ent mutants. These assays also showed that the dhbB translational product is a bifunctional protein that is required for the biosynthesis of catechol siderophores such as enterobactin (Earhart, 1996) and anguibactin (Crosa & Walsh, 2002;Welch et al, 2000). This chromosomal region, which is part of the pMU73 insert DNA, also includes genes encoding predicted proteins that belong to the EntD and EntF family.…”

Section: Discussionmentioning

confidence: 99%

Genetic organization of an Acinetobacter baumannii chromosomal region harbouring genes related to siderophore biosynthesis and transport

et al. 2003

Self Cite

View full text Add to dashboard Cite

The Acinetobacter baumannii 8399 clinical isolate secretes dihydroxybenzoic acid (DHBA) and a high-affinity catechol siderophore, which is different from other bacterial iron chelators already characterized. Complementation assays with enterobactin-deficient Escherichia coli strains led to the isolation of a cosmid clone containing A. baumannii 8399 genes required for the biosynthesis and activation of DHBA. Accordingly, the cloned fragment harbours a dhbACEB polycistronic operon encoding predicted proteins highly similar to several bacterial proteins required for DHBA biosynthesis from chorismic acid. Genes encoding deduced proteins related to the E. coli Fes and the Bacillus subtilis DhbF proteins, and a putative Yersinia pestis phosphopantetheinyl transferase, all of them involved in the assembly and utilization of catechol siderophores in other bacteria, were found next to the dhbACEB locus. This A. baumannii 8399 gene cluster also contained the om73, p45 and p114 predicted genes encoding proteins potentially involved in transport of ferric siderophore complexes. The deduced products of the p114 and p45 genes are putative membrane proteins that belong to the RND and MFS efflux pump proteins, respectively. Interestingly, P45 is highly related to the E. coli P43 (EntS) protein that participates in the secretion of enterobactin. Although P114 is similar to other bacterial efflux pump proteins involved in antibiotic resistance, its genetic arrangement within this A. baumannii 8399 locus is different from that described in other bacteria. The product of om73 is a Fur-and iron-regulated surface-exposed outer-membrane protein. These characteristics together with the presence of a predicted TonB box and its high similarity to other siderophore receptors indicate that OM73 plays such a role in A. baumannii 8399. The 184 nt om73-p114 intergenic region contains promoter elements that could drive the expression of these divergently transcribed genes, all of which are in close proximity to almost perfect Fur boxes. This arrangement explains the iron-and Fur-regulated expression of om73, and provides strong evidence for a similar regulation for the expression of p114. INTRODUCTIONBacteria survive and multiply under iron-limiting conditions, such as those found in natural and medical environments, by expressing active systems that gather this micronutrient, which is essential for most micro-organisms with some exceptions such as lactobacilli. Some systems involve the secretion of low-molecular-mass ferric-binding compounds called siderophores, which can be classified into different categories based on their chemical structure (Neilands, 1981(Neilands, , 1995. Many of these high-affinity ironchelating molecules contain catecholate groups that are part of the iron-binding site. Enterobactin, the prototype catechol siderophore produced by Escherichia coli, is a cyclic trimer of 2,3-dihydroxybenzoyl-L-serine (O'Brien & Gibson, 1970;Walsh et al., 1990). In contrast, siderophores such as vibriobactin and anguibactin, produced by...

show abstract

Section: Discussionmentioning

confidence: 99%

Genetic organization of an Acinetobacter baumannii chromosomal region harbouring genes related to siderophore biosynthesis and transport

et al. 2003

Self Cite

View full text Add to dashboard Cite

show abstract

“…Like EntB, the amino terminus of AngB possesses the isochorismate lyase activity (ICL in Fig. 11A), thereby explaining the need for this protein for the synthesis of DHBA (131). Analysis of mutations in the angB open reading frame provided evidence that in addition to angB, an overlapping gene, angG, exists at this locus and that it encodes three polypeptides which are in frame to the carboxy-terminal end of the 33-kDa AngB.…”

Section: Enzymologymentioning

confidence: 99%

“…Under iron-rich conditions, the Fe 2ϩ -Fur complexes bind to promoters containing a Fur box (Fur binding sequence) and repress transcription. Although Fur is required for transcriptional activation of some genes, this effect may be indirect (12,90,117,131). Fur homologues have been identified in Esche-richia coli and many other Gram-negative bacteria (12,25).…”

Section: Introductionmentioning

confidence: 99%

Genetics and Assembly Line Enzymology of Siderophore Biosynthesis in Bacteria

Crosa

Walsh

2002

Microbiol Mol Biol Rev

Self Cite

726

697

View full text Add to dashboard Cite

The regulatory logic of siderophore biosynthetic genes in bacteria involves the universal repressor Fur, which acts together with iron as a negative regulator. However in other bacteria, in addition to the Fur-mediated mechanism of regulation, there is a concurrent positive regulation of iron transport and siderophore biosynthetic genes that occurs under conditions of iron deprivation. Despite these regulatory differences the mechanisms of siderophore biosynthesis follow the same fundamental enzymatic logic, which involves a series of elongating acyl-S-enzyme intermediates on multimodular protein assembly lines: nonribosomal peptide synthetases (NRPS). A substantial variety of siderophore structures are produced from similar NRPS assembly lines, and variation can come in the choice of the phenolic acid selected as the N-cap, the tailoring of amino acid residues during chain elongation, the mode of chain termination, and the nature of the capturing nucleophile of the siderophore acyl chain being released. Of course the specific parts that get assembled in a given bacterium may reflect a combination of the inventory of biosynthetic and tailoring gene clusters available. This modular assembly logic can account for all known siderophores. The ability to mix and match domains within modules and to swap modules themselves is likely to be an ongoing process in combinatorial biosynthesis. NRPS evolution will try out new combinations of chain initiation, elongation and tailoring, and termination steps, possibly by genetic exchange with other microorganisms and/or within the same bacterium, to create new variants of iron-chelating siderophores that can fit a particular niche for the producer bacterium

show abstract

“…In some V. anguillarum strains, the chromosomal angA gene is present in a cluster with the other DHBA biosynthetic genes since these strains still produce DHBA when cured from the plasmid (174,175). In the case of V. anguillarum 531A, curing of the plasmid abolishes DHBA production, pointing to an incomplete chromosomally encoded DHBA cluster (176). The plasmid also carries the genes for the synthesis of N-hydroxyhistamine from histidine.…”

Section: Anguibactin Biosynthesismentioning

confidence: 99%

“…Activated DHBA is then tethered to the ArCP domain of AngG to further continue its assembly in the anguibactin molecule (100,175,176,179). The angG gene is transcribed from the same promoter as angB and can be found in one polypeptide with AngB but also as a separate polypeptide (176).…”

Section: Anguibactin Biosynthesismentioning

confidence: 99%

Plasmid-Encoded Iron Uptake Systems

Lorenzo

Stork

2014

Microbiol Spectr

View full text Add to dashboard Cite

Plasmids confer genetic information that benefits the bacterial cells containing them. In pathogenic bacteria, plasmids often harbor virulence determinants that enhance the pathogenicity of the bacterium. The ability to acquire iron in environments where it is limited, for instance the eukaryotic host, is a critical factor for bacterial growth. To acquire iron, bacteria have evolved specific iron uptake mechanisms. These systems are often chromosomally encoded, while those that are plasmid-encoded are rare. Two main plasmid types, ColV and pJM1, have been shown to harbor determinants that increase virulence by providing the cell with essential iron for growth. It is clear that these two plasmid groups evolved independently from each other since they do not share similarities either in the plasmid backbones or in the iron uptake systems they harbor. The siderophores aerobactin and salmochelin that are found on ColV plasmids fall in the hydroxamate and catechol group, respectively, whereas both functional groups are present in the anguibactin siderophore, the only iron uptake system found on pJM1-type plasmids. Besides siderophore-mediated iron uptake, ColV plasmids carry additional genes involved in iron metabolism. These systems include ABC transporters, hemolysins, and a hemoglobin protease. ColV-and pJM1-like plasmids have been shown to confer virulence to their bacterial host, and this trait can be completely ascribed to their encoded iron uptake systems.

show abstract

The Overlapping angB and angG Genes Are Encoded within the trans -Acting Factor Region of the Virulence Plasmid in Vibrio anguillarum : Essential Role in Siderophore Biosynthesis

Cited by 41 publications

References 52 publications

Genetic organization of an Acinetobacter baumannii chromosomal region harbouring genes related to siderophore biosynthesis and transport

Genetic organization of an Acinetobacter baumannii chromosomal region harbouring genes related to siderophore biosynthesis and transport

Genetics and Assembly Line Enzymology of Siderophore Biosynthesis in Bacteria

Plasmid-Encoded Iron Uptake Systems

Contact Info

Product

Resources

About