CadA negatively regulates Escherichia coli O157:H7 adherence and intestinal colonization.
Adherence of pathogenic Escherichia coli strains to intestinal epithelia is essential for infection. For enterohemorrhagic E. coli (EHEC) serotype O157:H7, we have previously demonstrated that multiple factors govern this pathogen's adherence to HeLa cells (A. G. Torres and J. B. Kaper, Infect. Immun. 71:4985-4995, 2003). One of these factors is CadA, a lysine decarboxylase, and this protein has been proposed to negatively regulate virulence in several enteric pathogens. In the case of EHEC strains, CadA modulates expression of the intimin, an outer membrane adhesin involved in pathogenesis. Here, we inactivated cadA in O157:H7 strain 86-24 to investigate the role of this gene in EHEC adhesion to tissue-cultured monolayers, global gene expression patterns, and colonization of the infant rabbit intestine. The cadA mutant did not possess lysine decarboxylation activity and was hyperadherent to tissue-cultured cells. Adherence of the cadA mutant was nearly twofold greater than that of the wild type, and the adherence phenotype was independent of pH, lysine, or cadaverine in the media. Additionally, complementation of the cadA defect reduced adherence back to wild-type levels, and it was found that the mutation affected the expression of the intimin protein. Disruption of the eae gene (intimin-encoding gene) in the cadA mutant significantly reduced its adherence to tissue-cultured cells. However, adherence of the cadA eae double mutant was greater than that of an 86-24 eae mutant, suggesting that the enhanced adherence of the cadA mutant is not entirely attributable to enhanced expression of intimin in this background. Gene array analysis revealed that the cadA mutation significantly altered EHEC gene expression patterns; expression of 1,332 genes was downregulated and that of 132 genes was upregulated in the mutant compared to the wild-type strain. Interestingly, the gene expression variation shows an EHEC-biased gene alteration including intergenic regions. Two putative adhesins, flagella and F9 fimbria, were upregulated in the cadA mutant, suggestive of their association with adherence in the absence of the Cad regulatory mechanism. In the infant rabbit model, the cadA mutant outcompeted the wild-type strain in the ileum but not in the cecum or mid-colon, raising the possibility that CadA negatively regulates EHEC pathogenicity in a tissue-specific fashion.
Vazquez-Juarez
Roberto C
RC
Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555-1070, USA.
Kuriakose
Jeeba A
JA
Rasko
David A
DA
Ritchie
Jennifer M
JM
Kendall
Melissa M
MM
Slater
Terry M
TM
Sinha
Mala
M
Luxon
Bruce A
BA
Popov
Vsevolod L
VL
Waldor
Matthew K
MK
Sperandio
Vanessa
V
Torres
Alfredo G
AG
D018829:Adhesins, Bacterial / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D001422:Bacterial Adhesion / Q000502:physiology*; D015153:Blotting, Western; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D019453:Escherichia coli O157 / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics; D015870:Gene Expression; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D020411:Oligonucleotide Array Sequence Analysis; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018829:Adhesins, Bacterial; D029968:Escherichia coli Proteins; C073819:eaeA protein, E coli; D002262:Carboxy-Lyases; C021520:lysine decarboxylase
Infect Immun. 2006 Apr;74(4):2233-44
16552054
Infect Immun. 2002 Oct;70(10):5416-27
12228266
J Bacteriol. 1992 Jan;174(2):530-40
1370290
Nat Genet. 2000 May;25(1):25-9
10802651
Mol Microbiol. 2002 Apr;44(2):361-79
11972776
Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6640-5
10829079
Proc Natl Acad Sci U S A. 1999 Dec 21;96(26):15196-201
10611361
Infect Immun. 2003 Sep;71(9):4985-95
12933841
Int J Med Microbiol. 2006 Dec;296(8):547-52
17027337
Nature. 1970 Aug 15;227(5259):680-5
5432063
Cell Microbiol. 1999 Sep;1(2):143-55
11207548
Infect Immun. 2005 Jan;73(1):18-29
15618137
Infect Immun. 2005 Aug;73(8):4766-76
16040989
J Vet Med Sci. 2007 Dec;69(12):1215-22
18176015
J Bacteriol. 2007 Mar;189(6):2249-61
17209032
J Bacteriol. 2001 May;183(9):2823-33
11292802
Nat Rev Microbiol. 2004 Feb;2(2):123-40
15040260
Infect Immun. 2005 Mar;73(3):1466-74
15731044
Int J Med Microbiol. 2007 Feb;297(1):17-26
17157559
Clin Microbiol Rev. 1998 Jan;11(1):142-201
9457432
Anaerobe. 2009 Feb-Apr;15(1-2):1-6
18572426
Mol Microbiol. 2002 Aug;45(4):951-66
12180916
Mol Microbiol. 1996 May;20(3):605-11
8736539
Infect Immun. 2007 Oct;75(10):4875-84
17635870
J Bacteriol. 2007 Oct;189(20):7426-35
17693516
J Bacteriol. 1992 Apr;174(8):2659-69
1556085
Proc Natl Acad Sci U S A. 1998 Mar 31;95(7):3943-8
9520472
J Infect Dis. 1989 Feb;159(2):344-7
2644374
Methods. 2001 Dec;25(4):402-8
11846609
FEMS Microbiol Lett. 2004 Sep 15;238(2):333-44
15358418
FEMS Microbiol Lett. 1997 Feb 15;147(2):173-80
9119190
Microbiology (Reading). 2007 Jul;153(Pt 7):2321-2331
17600076
J Clin Microbiol. 2003 Jul;41(7):3450
12843119
Mem Inst Oswaldo Cruz. 2002 Dec;97(8):1085-9
12563470
Cell Microbiol. 2008 Apr;10(4):836-47
18067584
J Clin Microbiol. 2004 Feb;42(2):903-5
14766885
Nucleic Acids Res. 1988 Jul 11;16(13):6127-45
3041370
J Infect Dis. 2001 Sep 15;184(6):743-53
11517436