Regulation of toxA and regA by the Escherichia coli fur gene and identification of a Fur homologue in Pseudomonas aeruginosa PA103 and PA01.
A multicopy plasmid containing the Escherichia coli fur gene was introduced into Pseudomonas aeruginosa strain PA103C. This strain contains a toxA-lacZ fusion integrated into its chromosome at the toxA locus. Beta-galactosidase synthesis in this strain is regulated by iron, as is seen for exotoxin A production. Beta-galactosidase synthesis and exotoxin A production in PA103C containing multiple copies of E. coli fur was still repressed in low iron conditions. The transcription of regA, a positive regulator of toxA, was also found to be inhibited by multiple copies of the E. coli fur gene. In addition, the ability of PA103C containing multiple copies of E. coli fur to produce protease was greatly reduced relative to PA103C containing a vector control. A polyclonal rabbit serum containing antibodies that recognize E. coli Fur was used to screen whole-cell extracts from Vibrio cholerae, Shigella flexneri, Salmonella typhimurium and Pseudomonas aeruginosa. All strains tested expressed a protein that was specifically recognized by the anti-Fur serum. These results and those described above suggest that Fur structure and function are conserved in a variety of distinct bacterial genera and that at least some of these different genera use this regulatory protein to control genes encoding virulence factors.
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Department of Microbiology and Immunology, University of Colorado Health Sciences Center, Denver 80262.
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D036002:ADP Ribose Transferases; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001427:Bacterial Toxins; D001483:Base Sequence; D016384:Consensus Sequence; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005098:Exotoxins / Q000096:biosynthesis / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D005098:Exotoxins; D007501:Iron; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A; C072722:RegA protein, Bacteria; C068477:ferric uptake regulating proteins, bacterial