Plasmids pJM1 and pColV-K30 Harbor Iron Uptake Genes That Are Essential for Bacterial Virulence

Jorge H. Crosa

doi:10.1128/9781555817732.ch24

Chapter 24 : Plasmids pJM1 and pColV-K30 Harbor Iron Uptake Genes That Are Essential for Bacterial Virulence

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Affiliations: 1: Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97201

Content Type: Monograph

Publication Year: 2004

Category: Microbial Genetics and Molecular Biology

Book DOI: 10.1128/9781555817732

Chapter DOI: 10.1128/9781555817732.ch24

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Abstract:

This chapter describes the analysis of pJM1 plasmid and pCoIV-K30 plasmid-mediated iron uptake systems. The iron transport-biosynthesis operon (ITBO) and other anguibactin biosynthetic genes located downstream are bracketed by the highly related ISV-A1 and ISV-A2 insertion sequences. The peptide siderophore anguibactin is synthesized via a nonribosomal peptide synthetase mechanism, an RNA-independent template chain growth process with an assembly line organization of different catalytic and carrier protein domains whose placement and function determine the number and sequence of the amino and carboxylic acids incorporated into the peptide product. Anguibactin can be thought as derived from the precursors dihydroxy benzoic acid (DHBA), histidine, and cysteine. The pJM1 plasmid-mediated proteins AngR, AngM, and AngN play a role in subsequent biosynthetic steps although AngR, in addition to its biosynthetic function, is also essential for regulation of iron transport gene expression. By deletion analysis the TAFr region has been narrowed down to two small subregions that could harbor this TAFr factor. At high iron concentrations iron represses the ITBO mRNA levels and concomitantly induces the synthesis of another antisense RNA (RNAα) that might constitute another novel component of the bacterial iron regulatory circuit. The genetic determinants for the aerobactin iron uptake system of plasmid pColV-K30 were cloned as recombinant plasmid pABN1.

Citation: Crosa J. 2004. Plasmids pJM1 and pColV-K30 Harbor Iron Uptake Genes That Are Essential for Bacterial Virulence, p 493-506. In Funnell B, Phillips G (ed), Plasmid Biology. ASM Press, Washington, DC. doi: 10.1128/9781555817732.ch24

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Plasmids pJM1 and pColV-K30 Harbor Iron Uptake Genes That Are Essential for Bacterial Virulence

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Figure 1

Structure of the siderophores anguibactin, aerobactin, and enterobactin.

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Figure 1

Structure of the siderophores anguibactin, aerobactin, and enterobactin.

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Figure 2

Schematic representation of the pJM1 plasmid. angM, -R, -T, -N, and -B are biosynthetic genes. angR is also a regulatory gene; together with the TAFr regulator they controlled expression of the fatD, -C, -B, -A, angR, angT operon named the ITBO. fatD, -C, -B, and -A are the ferric anguibactin transport genes.

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Figure 2

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Figure 3

Sites of action of Fur on the ITBO promoter. Top and bottom strands represent the nontemplate and template strand, respectively. The protected nucleotides in the DNase I footprint are denoted with an asterisk, and the hypersensitive sites are indicated by vertical arrows. The horizontal arrow indicates the transcription start site (+1) and the direction of transcription in the ITBO. Numbers are nucleotides relative to the transcription start site.

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Figure 3

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Figure 4

Schematic representation of the current understanding of the regulation of transport and biosynthesis genes in V. anguillarum. See text for details.

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Figure 4

Schematic representation of the current understanding of the regulation of transport and biosynthesis genes in V. anguillarum. See text for details.

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Figure 5

Schematic representation of the pColV-K30 plasmid. The aerobactin system region harbors the biosynthetic genes for aerobactin, iucA, -B, -C, and -D and the ferric-aerobactin transport gene iutA. Also shown are the regions encoding the genes for colicinV production (colV), conjugative transfer (tra), replication (REPI and REPII), and the various locations for the insertion element IS1 ( 69 ).

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Figure 5

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Figure 6

The aerobactin biosynthesis transport operon, iucA encodes a 63-kDa protein and iucC a 62-kDa protein that are involved in the synthetase reaction from N epsilon-acetyl-N epsilon-hydroxylysine and citrate; iucB encodes a 33-kDa polypeptide with the activity epsilon-hydroxylysine:acetyl coenzyme A-epsilon transacetylase and iucD encodes a 53-kDa polypeptide a lysine oxygenase, respectively, while iutA encodes the 74-kDa outer membrane protein receptor for ferric aerobactin.

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Figure 6

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Figure 7

Comparison of the Fur-binding sites for the aerobactin operon in pColV-K30 (A) and in the chromosome of E. coli K1 (B). The arrows depict sequences that are inverted and repeated in locations around the sequences. Overlapping arrows indicate their occurrence in both the sense and antisense strands.

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Figure 7

References

/content/book/10.1128/9781555817732.chap24

1. Actis, L. A.,, W. Fish,, J. H. Crosa,, K. Kellerman,, S. R. Ellenberger,, F. M. Hauser,, and J. Sanders-Loehr. 1986. Characterization of anguibactin, a novel siderophore from Vibrio anguillarum 77 S (pJM1) J. Bacteriol. 167: 57– 65.

2. Actis, L. A.,, M. E. Tolmasky,, L. M. Crosa,, and J. H. Crosa. 1995. Characterization and regulation of the expression of FatB, an iron transport protein encoded by the pJM1 virulence plasmid. Mol. Microbiol. 17: 197– 204.

3. Actis, L. A.,, M. E. Tolmasky,, and J. H. Crosa,. 1999. Fish diseases and disorders, p. 523– 557. In P. T. K. Woo, and D. W. Bruno (ed.), Viral, Bacterial and Fungal Infections. Cab International Publishing, Wallingford, United Kingdom.

4. Bindereif, A.,, V. Braun,, and K. Hantke. 1982. The cloacin receptor of ColV-bearing Escherichia coli is part of the Fe 3+ aerobactin transport system. J. Bacteriol. 150: 1472– 1475.

5. Bindereif, A.,, and J. B. Neilands. 1984, Aerobactin genes in clinical isolates of Escherichia coli. Infect. Immun. 46: 835– 838.

6. Bindereif, A.,, and J. B. Neilands. 1982. Cloning of the aerobactin-mediated iron assimilation system of plasmid ColV. Biochemistry 21: 7503– 6508.

7. Bindereif, A.,, and J. B. Neilands. 1985. Promoter mapping and transcriptional regulation of the iron assimilation system of plasmid ColV-K30 in Escherichia coli K-12. J. Bacteriol. 161: 727– 735.

8. Braun, V., and R. Burkhardt. 1982. Regulation of the ColV plasmid-determined iron (III)-aerobactin transport system in Escherichia coli. J. Bacteriol. 152: 223– 231.

9. Butterton, J. R.,, J. A. Stoebner,, S. M. Payne,, and S. B. Calderwood. 1992. Cloning, sequencing, and transcriptional regulation of viuA, the gene encoding the ferric vibriobactin receptor of Vibrio cholerae. J. Bacteriol. 174: 3728– 3738.

10. Carbonetti, N. H.,, and P. H. Williams. 1984. A cluster of five genes specifying the aerobactin iron uptake system of plasmid ColV-K30. Infect. Immun. 46: 7– 12.

11. Chai, S.,, T. Welch,, and J. H, Crosa. 1998. Characterization of the interaction between Fur and the iron transport promoter of the virulence plasmid in Vibrio anguillarum. J. Biol. Chem. 273: 33841– 33847.

12. Chen, Q.,, L. A. Actis,, M. E. Tolmasky,, and J. H. Crosa. 1994. Chromosome-mediated 2,3-dihydroxybenzoic acid is a precursor in the biosynthesis of the plasmid-mediated siderophore anguibactin in Vibrio anguillarum. J. Bacteriol. 176: 4226– 4234.

13. Chen, Q.,, and J. H. Crosa. 1996. Antisense RNA, Fur, iron, and the regulation of iron transport genes in Vibrio anguillarum. J. Biol. Chem. 271: 1885– 1891.

14. Chen, Q.,, A. M. Wertheimer,, M. E. Tolmasky,, and J. H. Crosa. 1996. The AngR protein and the siderophore anguibactin positively regulate the expression of iron-transport genes in Vibrio anguillarum. Mol. Microbiol. 22: 127– 134.

15. Colonna, B.,, M. Nicoletti,, P. Visca,, M. Casalino,, P. Valenti,, and F. Maimone. 1985. Composite IS1 elements encoding hydroxamate-mediated iron uptake in FIme plasmids from epidemic Salmonella spp. J. Bacteriol. 162: 307– 316.

16. Coulton, J. W.,, P. Mason,, and D. D. Allatt. 1987. fhuC and fhuD genes for iron (III)-ferrichrome transport into Escherichia coli K-12. J. Bacteriol. 169: 3844– 3849.

17. Coy, M.,, B. H. Paw,, A. Bindereif,, and J. B. Neilands. 1986. Isolation and properties of N epsilon-hydroxylysine:acetyl coenzyme A N epsilon-transacetylase from Escherichia coli pABN1I. Biochemistry. 25: 2485– 2489.

18. Crosa, J. H. 1980. A plasmid associated with virulence in the marine fish pathogen Vibrio anguillarum specifies an iron-sequestering system. Nature 284: 566– 568.

19. Crosa, J. H. 1997. Signal transduction and transcriptional and post-transcriptional control of iron-regulated genes in bacteria. Microbiol. Mol. Biol. Rev. 67: 319– 336.

20. Crosa, J. H.,, and L. L. Hodges. 1981. Outer membrane proteins induced under conditions of iron limitation in the marine fish pathogen Vibrio anguillarum 775. Infect. Immun. 31: 223– 227.

21. Crosa, J. H.,, L. L. Hodges,, and M. H. Schiewe. 1980. Curing of a plasmid is correlated with an attenuation of virulence in the marine fish pathogen Vibrio anguillarum. Infect. Immun. 27: 897– 902.

22. Crosa, J. H.,, and C. T. Walsh. 2002. Genetics and assembly line enzymology of siderophore biosynthesis in bacteria. Microbiol. Mol. Biol. Rev. 66: 223– 249.

23. Crosa, J. H.,, T. J. Welch,, L. A. Actis,, and M. E. Tolmasky. In Reddy, Breznak, Schmidt, S. Maloy, T. Beveridge, and Marzluf (ed.), Methods for General and Molecular Microbiology, 2nd ed., in press. ASM Press, Washington D. C..

24. Crosa, L. M.,, M. K. Wolf,, L. A. Actis,, J. Sanders-Loehr,, and J. H. Crosa. 1988. New aerobactin-mediated iron uptake system in a septicemia-causing strain of Enterobacter cloacae. J. Bacteriol. 170: 5529– 5538.

25. de Lorenzo, V.,, A. Bindereif,, B. H. Paw,, and J. B. Neilands. 1986. Aerobactin biosynthesis and transport genes of plasmid ColV-K30 in Escherichia coli K-12. J. Bacteriol. 165: 570– 578.

26. de Lorenzo, V.,, F. Giovannini,, M. Herrero,, and J. B. Neilands. 1988. Metal ion regulation of gene expression. Fur repressor-operator interaction at the promoter region of the aerobactin system of pColV-K30. J. Mol. Biol. 203: 875– 884.

27. de Lorenzo, V.,, M. Herrero,, and J. B. Neilands. 1988. IS 1-mediated mobility of the aerobactin system of pColV-K30 in Escherichia coli. Mol. Gen. Genet. 213: 487– 490.

28. de Lorenzo, V.,, and J. B. Neilands. 1986. Characterization of iucA and iucC genes of the aerobactin system of plasmid ColV-K30 in Escherichia coli. J. Bacteriol. 167: 350– 355.

29. de Lorenzo, V.,, S. Wee,, M. Herrero,, and J. B. Neilands. 1987. Operator sequences of the aerobactin operon of plasmid ColV-K30 binding the ferric uptake regulation (fur) repressor. J. Bacteriol. 169: 2624– 2630.

30. Dorsey, C.,, J. R. Echenique,, J. C. Smmot,, R. H. Findlay,, M. E. Tolmasky,, L. A. Actis,, and J. H. Crosa. The human pathogen Acinetobacter baumannii shares components of the anguibactin-mediated iron acquisition system that plays an important role in the virulence of the fish pathogen Vibrio anguillarum. Infect. Immun., in press.

31. Enz, S.,, V. Braun,, and J. H. Crosa. 1995. Transcription of the region encoding the ferric dicitrate-transport system in Escherichia coli: similarity between promoter for fecA and for extracytoplasmic function sigma factors. Gene 163: 13– 18.

32. Farrell, D. H.,, P. Mikesell,, L. A. Actis,, and J. H. Crosa. 1990. A regulatory gene, angR, of the iron uptake system of Vibrio anguillarum: similarity with phage P22 cro and regulation by iron. Gene 86: 45– 51.

33. Gibson F.,, and D. I. Magrath. 1969. The isolation and characterization of a hydroxamic acid (aerobactin) formed by Aerobacter aerogenes 62-1. Biochim. Biophys. Acta 192: 175– 184.

34. Goetz, D. H.,, M. A. Holmes,, N. Borregaard,, M. E. Bluhm,, K. N. Raymond,, and R. K. Strong. 2002. The neutrophil lipocalin NGAL is a bacteriostatic agent that interferes with siderophore-mediated iron acquisition. Mol. Cell 10: 1033– 1043.

35. Gross, R.,, F. Engelbrecht,, and V. Braun. 1984. Genetic and biochemical characterization of the aerobactin synthesis operon on pColV. Mol. Gen. Genet. 196: 74– 80.

36.Gross R., F. Engelbrecht, and V. Braun. 1985. Identification of the genes and their polypeptide products responsible for aerobactin synthesis by pColV plasmids. Mol. Gen. Genet. 201: 204– 212.

37. Honda, T.,, and R. A. Finkelstein. 1979. Purification and characterization of a hemolysin produced by Vibrio cholerae biotype El Tor: another toxic substance produced by cholera vibrios. Infect. Immun. 26: 1020– 1027.

38. Jalal, M. A.,, and D. Van der Helm. 1989. Purification and crystallization of ferric enterobactin receptor protein, fepA, from the outer membranes of Escherichia coli UT5600/pBB2. FEBS Lett. 243: 366– 370.

39. Konopka, K.,, A. Bindereif,, and J. B. Neilands. 1982. Aerobactin-mediated utilization of transferrin iron. Biochemistry 21: 6503– 6508.

40. Konopka, K.,, and J. B. Neilands. 1984. Effect of serum albumin on siderophore-mediated utilization of transferrin iron. Biochemistry 23: 2122– 2127.

41. Koster, W.,, L. A. Actis,, L. S. Waldbeser,, M. E. Tolmasky,, and J. H. Crosa. 1991. Molecular characterization of the iron transport system mediated by the pJM1 plasmid in Vibrio anguillarum 775. J. Biol. Chem. 266: 23829– 23833.

42. Linkous, D. A.,, and J. D. Oliver. 1999. Pathogenesis of Vibrio vulnificus. Microbiol. Lett. 174: 207– 214.

43. Marolda, C. L.,, M. A. Valvano,, K. M. Lawlor,, S. M. Payne,, and J. H. Crosa. 1987. Flanking and internal regions of chromosomal genes mediating aerobactin iron uptake systems in enteroinvasive Escherichia coli and Shigella flexneri. J. Gen. Microbiol. 133: 2269– 2278.

44. McDougall, S.,, and J. B. Neilands. 1983. Plasmid and chromosome-coded aerobactin synthesis in enteric bacteria: insertion sequences flank operon in plasmid-mediated systems. J. Bacteriol. 153: 1111– 1113.

45. Montgomerie, J. Z.,, A. Bindereif,, J. B. Neilands,, G. M. Kalmanson,, and L. B. Guze. 1984. Association of hydroxamate siderophore (aerobactin) with Escherichia coli isolated from patients with vacteremia. J. Bacteriol. 159: 300– 305.

46. Neilands, J. B. 1992. Mechanism and regulation of synthesis of aerobactin in Escherichia coli K12 (pColV-K30). Can. J. Microbiol. 38: 728– 733.

47. Poteete, A. R.,, K. Hehir,, and R. T. Sauer. 1986. Bacteriophage P22 Cro protein: sequence, purification, and properties. Biochemistry 25: 251– 256.

48. Salinas, P.,, and J. H. Crosa. 1995. Regulation of angR, a gene with regulatory and biosynthetic functions in the pJM1 plasmid-mediated iron uptake system of Vibrio anguillarum. Gene 160: 17– 23.

49. Salinas P. C.,, L. S. Waldbeser,, and J. H. Crosa. 1993. Regulation of the expression of bacterial iron transport genes: possible role of an antisense RNA as a repressor. Gene 123: 33– 38.

50. Smoot, L. M.,, E. C. Bell,, J. H. Crosa,, and L. A. Actis. 1999. Fur and iron transport proteins in the Brazilian purpuric fever clone of Haemophilus influenzae biogroup acgyptius. J. Med. Microbiol. 48: 629– 636.

51. Stephens, D. L.,, M. D. Choe,, and C. F. Earhart. 1995. Escherichia coli periplasmic protein FepB binds ferrienterobactin. Microbiology 141: 1647– 1654.

52. Strom, M. S.,, and R. N. Paranjpye. 2000. Epidemiology and pathogenesis of Vibrio vulnificus. Microb. Infect. 2: 177– 188.

53. Taniguchi, H.,, H. Ohta,, M. Ogawa,, and Y. Mizuguchi. 1985. Cloning and expression in Escherichia coli of Vibrio parahaemolyticus thermostable direct hemolysin and thermolabile hemolysin genes. J. Bacteriol. 162: 510– 515.

54. Tolmasky, M. E.,, L. A. Actis,, and J. H. Crosa,. 1999. Plasmid DNA replication. In M. C. Flickinger, and S. W. Drew (ed.), Encyclopedia of Bioprocess Technology: Fermentation, Biocatalysis and Bioseparation. John Wiley and Sons, Inc., New York, N.Y..

55. Tolmasky, M. E.,, L. A. Actis,, and J . H. Crosa. 1995. A histidine decarboxylase gene encoded by the Vibrio anguillarum plasmid pJM1 is essential for virulence: histamine is a precursor in the biosynthesis of anguibactin. Mol. Microbiol. 15: 87– 95.

56. Tolmasky, M. E.,, L. A. Actis,, and J. H. Crosa. 1988. Genetic analysis of the iron uptake region of the Vibrio anguillarum plasmid pJM1: molecular cloning of genetic determinants encoding a novel trans activator of siderophore biosynthesis. J. Bacteriol. 170: 1913– 1919.

57. Tolmasky, M. E.,, and J. H. Crosa. 1995. Iron transport genes of the pJM1-mediated iron uptake system of Vibrio anguillarum are included in a transposon-like structurE. Plasmid 33: 180– 190.

58. Tolmasky, M. E.,, and J. H. Crosa. 1991. Regulation of plasmid-mediated iron transport and virulence in Vibrio anguillarum. Biol. Met. 4: 33– 35.

59. Tolmasky, M. E.,, A. M. Wertheimer,, L. A. Actis,, and J. H. Crosa. 1994. Characterization of the Vibrio anguillarum fur gene: role in regulation of expression of the FatA outer membrane protein and catechols. J. Bacteriol. 176: 213– 220.

60. Valvano, M. A.,, and J. H. Crosa. 1984. Aerobactin iron transport genes commonly encoded by certain ColV plasmids occur in the chromosome of a human invasive strain of Escherichia coli K1. Infect. Immun. 46: 159– 167.

61. Valvano, M. A.,, and J . H. Crosa. 1988. Molecular cloning, expression, and regulation in Escherichia coli K-12 of a chromosome-mediated aerobactin iron transport system from a human invasive isolate of E. coli K1. J. Bacteriol. 170: 5153– 5160.

62. Valvano, M. A.,, R. P. Silver,, and J. H. Crosa. 1986. Occurrence of chromosome or plasmid-mediated aerobactin iron transport systems and hemolysin production among clonal groups of human invasive strains of Escherichia coli K1. Infect. Immun. 52: 192– 199.

63. Waldbeser, L. S.,, Q. Chen,, and J. H. Crosa. 1995. Antisense RNA regulation of the fatB iron transport protein gene in Vibrio anguillarum. Mol. Microbiol. 17: 747– 756.

64. Waller, M. A.,, A. Bindereif,, J. B. Neilands,, and J. H. Crosa. 1984. Lack of homology between the iron transport regions of two virulence-linked bacterial plasmids. Infect. Immun. 43: 765– 767.

65. Warner, P. J.,, P. H. Williams,, A. Bindereif,, and J. B. Neilands. 1981. ColV plasmid-specific aerobactin synthesis by invasive strains of E. coli. Infect. Immun. 33: 540– 545.

66. Waters, V. L.,, and J. H. Crosa. 1986. DNA environment of the aerobactin iron uptake system genes in prototypic ColV plasmids. J. Bacteriol. 167: 647– 654.

67. Waters, V. L.,, and J. H. Crosa. 1987. Divergence of the aerobactin iron uptake systems encoded by plasmids pColV-K30 in Escherichia coli K-12 and pSMN1 in Aerobacter aerogenes 62-1. J. Gen. Microbiol. 133: 2269– 2278.

68. Waters, V.,, and J . H. Crosa. 1991. Colicin V virulence plasmids. Microbiol. Rev. 55: 437– 450.

69. Waters, V. L.,, J. F. Perez-Casal,, and J. H. Crosa. 1989. ColV plasmids pColV-Bl88 and pColV-K30: genetic maps according to restriction enzyme sites and landmark phenotypic characteristics. Plasmid 22: 244– 248.

70. Welch, T. J.,, S. Chai,, and J. H. Crosa. 2000. The overlapping angB and angG genes are components of the transacting factor encoded by the virulence plasmid in Vibrio anguillarum: essential role in siderphore biosynthesis. J. Bacteriol. 182: 6762– 6773.

71. Wertheimer, A. M.,, M. E. Tolmasky,, L. A. Actis,, and J. H. Crosa. 1995. Structural and functional analysis of mutant Fur proteins with impaired regulatory function. J. Bacteriol. 176: 5116– 5122.

72. Wertheimer, A. M.,, W. Verwej,, Q. Chen,, L. M. Crosa,, M. Nagasawa,, M. E. Tolmasky,, L. A. Actis,, and J. H. Crosa. 1999. Characterization of the angR gene of Vibrio anguillarum: essential role in virulence. Infect. Immun. 67: 6496– 6509.

73. Williams, P. H, 1979. Novel iron uptake system specified by ColV plasmids: an important component in the virulence of invasive strains of Escherichia coli. Infect. Immun. 26: 925– 932.

74. Williams, P. H.,, and N. H. Carbonetti. 1984. Iron, siderophores, and the pursuit of virulence: independence of the aerobactin and enterobactin iron uptake systems in Escherichia coli. Infect. Immun. 46: 7– 12.

75. Wolf, M. K.,, and J. H. Crosa. 1986. Evidence for the role of a siderophore in promoting Vibrio anguillarum infections. J. Gen. Microbiol. 132: 2949– 2952.

76. Zheleznova, E. E.,, J. H. Crosa,, and R. G. Brennan. 2000. Characterization and metal binding properties of Vibrio anguillarum Fur reveals differences from E. coli Fur. J. Bacteriol. 182: 6264– 6267.