Transcriptional analysis of the grlRA virulence operon from Citrobacter rodentium.
The locus for enterocyte effacement (LEE) is the virulence hallmark of the attaching-and-effacing (A/E) intestinal pathogens, namely, enteropathogenic Escherichia coli, enterohemorrhagic E. coli, and Citrobacter rodentium. The LEE carries more than 40 genes that are arranged in several operons, e.g., LEE1 to LEE5. Expression of the various transcriptional units is subject to xenogeneic silencing by the histone-like protein H-NS. The LEE1-encoded regulator, Ler, plays a key role in relieving this repression at several major LEE promoters, including LEE2 to LEE5. To achieve appropriate intracellular concentrations of Ler in different environments, A/E pathogens have evolved a sophisticated regulatory network to control ler expression. For example, the LEE-encoded GrlA and GrlR proteins work as activator and antiactivator, respectively, of ler transcription. Thus, control of the transcriptional activities of the LEE1 (ler) promoter and the grlRA operon determines the rate of transcription of all of the LEE-encoded virulence factors. To date, only a single promoter has been identified for the grlRA operon. In this study, we showed that the non-LEE-encoded AraC-like regulatory protein RegA of C. rodentium directly stimulates transcription of the grlRA promoter by binding to an upstream region in the presence of bicarbonate ions. In addition, in vivo and in vitro transcription assays revealed a sigma(70) promoter that is specifically responsible for transcription of grlA. Expression from this promoter was strongly repressed by H-NS and its paralog StpA but was activated by Ler. DNase I footprinting demonstrated that Ler binds to a region upstream of the grlA promoter, whereas H-NS interacts specifically with a region extending from the grlA core promoter into its coding sequence. Together, these findings provide new insights into the environmental regulation and differential expressions of the grlR and grlA genes of C. rodentium.
Tauschek
Marija
M
Department of Microbiology and Immunology, the University of Melbourne, Parkville, Victoria 3010, Australia.
Yang
Ji
J
Hocking
Dianna
D
Azzopardi
Kristy
K
Tan
Aimee
A
Hart
Emily
E
Praszkier
Judyta
J
Robins-Browne
Roy M
RM
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002874:Chromosome Mapping; D044082:Citrobacter rodentium / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D004269:DNA, Bacterial; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics*; D017693:Sodium Bicarbonate; D024363:Transcription Initiation Site; D014158:Transcription, Genetic; D014774:Virulence
D001426:Bacterial Proteins; D004269:DNA, Bacterial; C072722:RegA protein, Bacteria; D017693:Sodium Bicarbonate
J Bacteriol. 2005 Jan;187(1):349-57
15601719
J Bacteriol. 2001 Feb;183(4):1259-68
11157938
J Bacteriol. 2001 May;183(9):2823-33
11292802
Proc Natl Acad Sci U S A. 1995 Feb 28;92(5):1664-8
7878036
Nat Rev Microbiol. 2004 May;2(5):391-400
15100692
Cell. 1991 Jun 14;65(6):1015-22
1646077
Microb Biotechnol. 2010 May;3(3):259-68
21255326
J Biol Chem. 2007 Aug 10;282(32):23622-30
17569663
Infect Immun. 2007 Sep;75(9):4199-210
17576759
Microbiology (Reading). 2005 Apr;151(Pt 4):1199-1208
15817787
Mol Microbiol. 2008 Apr;68(2):314-27
18284589
J Mol Biol. 2000 May 19;298(5):737-48
10801345
Mol Gen Genet. 1994 Oct 28;245(2):255-9
7816034
J Bacteriol. 1978 Jun;134(3):1141-56
149110
Infect Immun. 2000 Nov;68(11):6115-26
11035714
J Biomed Sci. 2004 Nov-Dec;11(6):855-63
15591783
J Bacteriol. 2005 Dec;187(23):7918-30
16291665
Mol Microbiol. 1999 Jul;33(2):296-306
10411746
Mol Microbiol. 2001 Feb;39(3):664-78
11169107
J Bacteriol. 2004 Nov;186(21):7290-301
15489441
Infect Immun. 2003 Jan;71(1):384-92
12496188
Mol Microbiol. 2003 Apr;48(2):507-21
12675808
Infect Immun. 1998 Aug;66(8):3810-7
9673266
Proc Natl Acad Sci U S A. 2004 May 4;101(18):6911-6
15118087
Cell Microbiol. 2005 Dec;7(12):1697-706
16309456
Infect Immun. 1993 Jun;61(6):2486-92
8500884
Infect Immun. 1995 May;63(5):1767-76
7729884
Microbiology (Reading). 2002 Sep;148(Pt 9):2735-2744
12213920
Infect Immun. 2001 Oct;69(10):6323-35
11553577
Microbes Infect. 2001 Apr;3(4):333-40
11334751
Microbiology (Reading). 2003 Aug;149(Pt 8):2093-2106
12904549
Proc Natl Acad Sci U S A. 1990 Oct;87(20):7839-43
2172966
PLoS Pathog. 2007 May 18;3(5):e69
17511515
J Biol Chem. 1987 May 5;262(13):6389-95
3032964
Mol Microbiol. 1999 Dec;34(5):941-52
10594820
J Bacteriol. 2005 Jan;187(2):458-72
15629917
Mol Microbiol. 1995 May;16(3):425-39
7565104
Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6640-5
10829079
J Bacteriol. 2007 Jul;189(14):5387-92
17496094
Mol Microbiol. 1998 Apr;28(1):1-4
9593291
Mol Microbiol. 2001 Aug;41(3):549-59
11532124
J Bacteriol. 1984 Apr;158(1):279-85
6325390
J Bacteriol. 1998 Dec;180(23):6117-25
9829919
Proc Natl Acad Sci U S A. 1999 Dec 21;96(26):15196-201
10611361
Proc Natl Acad Sci U S A. 2004 Mar 9;101(10):3597-602
14988506
J Mol Biol. 1976 Jul 5;104(3):541-55
781293
Mol Microbiol. 2000 May;36(4):962-72
10844682
Biochim Biophys Acta. 1998 Mar 4;1396(1):114-26
9524241
Mol Microbiol. 2000 Nov;38(4):781-93
11115113
Mol Gen Genet. 1981;184(3):548-50
6278264
J Mol Biol. 2009 Dec 11;394(4):591-9
19853617
J Bacteriol. 1994 Aug;176(15):4691-9
7913930
Gene. 1977;2(2):95-113
344137
Microbiology (Reading). 2008 Sep;154(Pt 9):2533-2545
18757787
Curr Opin Microbiol. 2008 Apr;11(2):113-20
18387844
Infect Immun. 2008 Nov;76(11):5247-56
18765720
Infect Immun. 2006 Apr;74(4):2328-37
16552063
Proc Natl Acad Sci U S A. 1989 Feb;86(3):963-7
2563591
Infect Immun. 2004 Apr;72(4):2329-37
15039358
J Bacteriol. 2002 Oct;184(19):5449-56
12218033
Nucleic Acids Res. 2000 May 1;28(9):1864-70
10756184
J Bacteriol. 2007 Jan;189(1):142-50
17085567