Plasmid- and chromosome-coded aerobactin synthesis in enteric bacteria: insertion sequences flank operon in plasmid-mediated systems

McDougall, Skye; Neilands, J. B.

doi:10.1128/jb.159.1.300-305.1984

Cited by 70 publications

(32 citation statements)

References 31 publications

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“…The same probes hybridized with a 16.3-kb HindIII fragment in the pColV-K30-harboring strain LG1315 (Fig. 2, lane m) (25,34). pZM3 and pZM111 are two naturally occurring, aerobactin-encoding IncFI virulence R plasmids originally isolated from S. wien epidemic strains (8).…”

Section: Discussionmentioning

confidence: 99%

Organization of aerobactin, hemolysin, and antibacterial resistance genes in lactose-negative Escherichia coli strains of serotype O4 isolated from children with diarrhea

et al. 1992

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26:524-529, 1988). In order to define the virulence potential of these strains, we characterized the replication properties of their high-molecular-weight plasmids and studied the genetic locations and organization of the aerobactin (aer) and hemolysin (hly) determinants encoded by 23 NLF 04 E. coli strains. Southern blot hybridizations, mobilization assays of nonconjugative plasmids, and incompatibility-exclusion experiments conducted with a conjugative incompatibility group FT (IncFI) plasmid showed that (i) 20 out of the 23 strains examined harbor a 160-to 180-kb IncFI plasmid that shares homology with the basic replicons RepFIA, RepFIB, and (except for the plasmid of one strain) RepFIC, and 22 strains also contain a 40to 140-kb IncFIl plasmid sharing homology with the RepFlIA replicon; (ii) the IncFI plasmid is nonconjugative and carries antibiotic resistance genes; (iii) the aer system is located on the IncFI plasmids and/or the chromosomes in the three strains not harboring IncFI, and it is found in an inverted orientation; (iv) the hly determinants are located on the chromosome, and their genetic organization is well conserved and on August 2, 2020 by guest http://iai.asm.org/ Downloaded from

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Section: Discussionmentioning

confidence: 99%

Organization of aerobactin, hemolysin, and antibacterial resistance genes in lactose-negative Escherichia coli strains of serotype O4 isolated from children with diarrhea

et al. 1992

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“…The mobility of the genes may be related to the presence of insertion sequences flanking the genes. Copies of IS 1 are found on either side of the pColV aerobactin genes (McDougall and Neilands, 1984), and the S. flexneri aerobactin genes are flanked by IS 2 elements. Movement of these genes does not appear to result from a simple transposition event, however, as the sequences immediately upstream and downstream of the genes and the position and type of associated insertion sequences are different in each case.…”

Section: Discussionmentioning

confidence: 99%

“…They are found on plasmids, including pColV (Williams, 1979) and F1 me (Colonna et al ., 1985) in certain strains of E. coli and Salmonella , respectively, but are chromosomal in Shigella spp. (Lawlor and Payne, 1984) and in other E. coli and Salmonella isolates (McDougall and Neilands, 1984; Marolda et al ., 1987).…”

Section: Introductionmentioning

confidence: 99%

The aerobactin iron transport system genes in Shigella flexneri are present within a pathogenicity island

Vokes

Reeves

Torres

et al. 1999

Molecular Microbiology

136

106

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Genes encoding the synthesis and transport of aerobactin, a hydroxamate siderophore associated with increased virulence of enteric bacteria, were mapped within a pathogenicity island in Shigella flexneri. The island, designated SHI‐2 for Shigella pathogenicity island 2, was located downstream of selC, the site of insertion of pathogenicity islands in several other enteric pathogens. DNA sequence analysis revealed the presence of multiple insertion sequences upstream and downstream of the aerobactin genes and an integrase gene that was nearly identical to an int gene found in Escherichia coli O157:H7. SHI‐2 sequences adjacent to selC were similar to sequences at the junction between selC and pathogenicity islands found in E. coli O157:H7 and in enteropathogenic E. coli, but the junctions between the island and downstream yic genes were variable. SHI‐2 also encoded immunity to the normally plasmid‐encoded colicins I and V, suggesting a common origin for the aerobactin genes in both S. flexneri and E. coli pColV. Polymerase chain reaction and Southern hybridization data indicate that SHI‐2 is present in the same location in Shigella sonnei, but the aerobactin genes are not located within SHI‐2 in Shigella boydii or enteroinvasive E. coli. Shigella dysenteriae type 1 strains do not produce aerobactin but do contain sequences downstream of selC that are homologous to SHI‐2. The presence of the aerobactin genes on plasmids in E. coli pColV and Salmonella, on a pathogenicity island in S. flexneri and S. sonnei and in a different chromosomal location in S. boydii and some E. coli suggests that these virulence‐enhancing genes are mobile, and they may constitute an island within an island in S. flexneri.

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“…Some products of unicellular bacteria are plasmid-encoded. These include aerobactin, a hydroxamate siderophore and virulence factor produced by Escherichia coli (McDougall & Neilands, 1984) and other Gram-negative bacteria (Enterobacter aerogenes, Enterobacter cloacae, Vibrio mimicus, and species of Klebsiella, Salmonella and Shigella). Aerobactin is synthesized by a plasmid-borne five-gene cluster, which is negatively regulated by iron (Roberts et al, 1986); it can also be produced via chromosomal genes (Moon et al, 2004).…”

Section: Plasmids Transposons Cosmids and Phagementioning

confidence: 99%

Genetic improvement of processes yielding microbial products

2006

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Although microorganisms are extremely good in presenting us with an amazing array of valuable products, they usually produce them only in amounts that they need for their own benefit; thus, they tend not to overproduce their metabolites. In strain improvement programs, a strain producing a high titer is usually the desired goal. Genetics has had a long history of contributing to the production of microbial products. The tremendous increases in fermentation productivity and the resulting decreases in costs have come about mainly by mutagenesis and screening/selection for higher producing microbial strains and the application of recombinant DNA technology.

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Plasmid- and chromosome-coded aerobactin synthesis in enteric bacteria: insertion sequences flank operon in plasmid-mediated systems

Cited by 70 publications

References 31 publications

Organization of aerobactin, hemolysin, and antibacterial resistance genes in lactose-negative Escherichia coli strains of serotype O4 isolated from children with diarrhea

Organization of aerobactin, hemolysin, and antibacterial resistance genes in lactose-negative Escherichia coli strains of serotype O4 isolated from children with diarrhea

The aerobactin iron transport system genes in Shigella flexneri are present within a pathogenicity island

Genetic improvement of processes yielding microbial products

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