title: The SdiA-regulated gene srgE encodes a type III secreted effector.
abstract: Salmonella enterica serovar Typhimurium is a food-borne pathogen that causes severe gastroenteritis. The ability of Salmonella to cause disease depends on two type III secretion systems (T3SSs) encoded in two distinct Salmonella pathogenicity islands, 1 and 2 (SPI1 and SPI2, respectively). S. Typhimurium encodes a solo LuxR homolog, SdiA, which can detect the acyl-homoserine lactones (AHLs) produced by other bacteria and upregulate the rck operon and the srgE gene. SrgE is predicted to encode a protein of 488 residues with a coiled-coil domain between residues 345 and 382. In silico studies have provided conflicting predictions as to whether SrgE is a T3SS substrate. Therefore, in this work, we tested the hypothesis that SrgE is a T3SS effector by two methods, a β-lactamase activity assay and a split green fluorescent protein (GFP) complementation assay. SrgE with β-lactamase fused to residue 40, 100, 150, or 300 was indeed expressed and translocated into host cells, but SrgE with β-lactamase fused to residue 400 or 488 was not expressed, suggesting interference by the coiled-coil domain. Similarly, SrgE with GFP S11 fused to residue 300, but not to residue 488, was expressed and translocated into host cells. With both systems, translocation into host cells was dependent upon SPI2. A phylogenetic analysis indicated that srgE is found only within Salmonella enterica subspecies. It is found sporadically within both typhoidal and nontyphoidal serovars, although the SrgE protein sequences found within typhoidal serovars tend to cluster separately from those found in nontyphoidal serovars, suggesting functional diversification.
authors.affiliation: Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Fabien
authors.initials: F
authors.lastname: Habyarimana
authors.affiliation: Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Anice
authors.initials: A
authors.lastname: Sabag-Daigle
authors.affiliation: Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, USA Department of Microbiology, The Ohio State University, Columbus, Ohio, USA ahmer.1@osu.edu.
authors.forename: Brian M M
authors.initials: BM
authors.lastname: Ahmer
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004926:Escherichia coli / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010802:Phylogeny; D011994:Recombinant Proteins; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; C440638:SPI-2 protein, Salmonella; C097686:SdiA protein, bacteria; C419942:Spi1 protein, Salmonella; D015534:Trans-Activators
references.citation: Nat Rev Microbiol. 2008 Jan;6(1):53-66
references.pmid: 18026123
references.citation: J Mol Biol. 2010 Mar 12;396(5):1392-7
references.pmid: 20060835
references.citation: Mol Biosyst. 2010 Dec;6(12):2448-58
references.pmid: 20877914
references.citation: Proc Natl Acad Sci U S A. 2011 Oct 18;108(42):17480-5
references.pmid: 21969563
references.citation: Infect Immun. 2013 Apr;81(4):1207-20
references.pmid: 23357385
references.citation: mBio. 2012 May 29;3(3):
references.pmid: 22647788
references.citation: Mol Microbiol. 1995 Jan;15(1):25-38
references.pmid: 7752894
references.citation: Res Microbiol. 2010 Jan-Feb;161(1):26-9
references.pmid: 19840847
references.citation: PLoS One. 2011;6(6):e21648
references.pmid: 21738750
references.citation: PLoS Pathog. 2009 Apr;5(4):e1000375
references.pmid: 19390620
references.citation: Berl Munch Tierarztl Wochenschr. 2007 Jul-Aug;120(7-8):317-27
references.pmid: 17715824
references.citation: PLoS Pathog. 2013;9(11):e1003730
references.pmid: 24278012
references.citation: PLoS Pathog. 2009 Jul;5(7):e1000477
references.pmid: 19578432
references.citation: Cell Microbiol. 2002 Jan;4(1):43-54
references.pmid: 11856172
references.citation: mBio. 2014 Mar 18;5(2):e00929-14
references.pmid: 24643865
references.citation: Mol Microbiol. 1998 Oct;30(1):163-74
references.pmid: 9786193
references.citation: FASEB J. 2012 Apr;26(4):1569-81
references.pmid: 22210834
references.citation: PLoS Pathog. 2011 Aug;7(8):e1002191
references.pmid: 21876672
references.citation: Biochem Soc Trans. 1994 May;22(2):301-6
references.pmid: 7958312
references.citation: J Bacteriol. 2001 Oct;183(20):6036-45
references.pmid: 11567004
references.citation: Curr Microbiol. 2011 Jul;63(1):22-31
references.pmid: 21487806
references.citation: Science. 2010 May 21;328(5981):1040-3
references.pmid: 20395475
references.citation: New Phytol. 2012 Jun;194(4):1046-1060
references.pmid: 22471508
references.citation: Chem Biol. 2008 Jun;15(6):619-28
references.pmid: 18559272
references.citation: Mol Biosyst. 2008 Nov;4(11):1105-15
references.pmid: 18931786
references.citation: Nature. 2010 Sep 23;467(7314):426-9
references.pmid: 20864996
references.citation: J Biol Chem. 2007 Nov 23;282(47):33897-901
references.pmid: 17911114
references.citation: Infect Immun. 2005 Jun;73(6):3228-41
references.pmid: 15908347
references.citation: Cell Microbiol. 2011 Dec;13(12):1858-69
references.pmid: 21902796
references.citation: Future Microbiol. 2010 Oct;5(10):1525-38
references.pmid: 21073312
references.citation: EMBO Rep. 2013 Apr;14(4):319-27
references.pmid: 23478337
references.citation: Nature. 1993 Aug 12;364(6438):639-42
references.pmid: 8350922
references.citation: J Bacteriol. 2013 Jan;195(2):173-9
references.pmid: 23144246
references.citation: Cell Res. 2010 Jun;20(6):647-64
references.pmid: 20368731
references.citation: Infect Immun. 2006 Sep;74(9):5047-57
references.pmid: 16926396
references.citation: PLoS Biol. 2007 Oct;5(10):2177-89
references.pmid: 17760501
references.citation: J Immunol. 2005 Feb 1;174(3):1675-85
references.pmid: 15661931
references.citation: J Exp Med. 1994 Feb 1;179(2):601-8
references.pmid: 8294870
references.citation: Microbiology (Reading). 2010 Apr;156(Pt 4):1120-1133
references.pmid: 20035008
references.citation: J Bacteriol. 2003 Dec;185(24):7257-65
references.pmid: 14645287
references.citation: Science. 2011 Mar 4;331(6021):1188-91
references.pmid: 21292939
references.citation: Mol Microbiol. 1998 Oct;30(1):175-88
references.pmid: 9786194
references.citation: Curr Opin Microbiol. 1999 Feb;2(1):46-50
references.pmid: 10047557
references.citation: PLoS Pathog. 2009 Apr;5(4):e1000376
references.pmid: 19390696
references.citation: Nat Rev Microbiol. 2013 Apr;11(4):277-84
references.pmid: 23474681
references.citation: Infect Immun. 2003 Jan;71(1):1-12
references.pmid: 12496143
references.citation: Microbiologia. 1994 Sep;10(3):229-38
references.pmid: 7873099
references.citation: PLoS One. 2013 May 14;8(5):e63917
references.pmid: 23691117
references.citation: Mol Microbiol. 1999 Aug;33(4):806-16
references.pmid: 10447889
references.citation: Proc Natl Acad Sci U S A. 2000 Oct 24;97(22):12283-8
references.pmid: 11050248
references.citation: J Bacteriol. 2003 Feb;185(4):1357-66
references.pmid: 12562806
references.citation: Infect Immun. 1999 Nov;67(11):5690-8
references.pmid: 10531217
references.citation: Cell Microbiol. 2009 May;11(5):719-29
references.pmid: 19215225
references.citation: Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6640-5
references.pmid: 10829079
references.citation: Immunol Rev. 2012 Jan;245(1):56-83
references.pmid: 22168414
references.citation: Cell Microbiol. 2007 Sep;9(9):2103-11
references.pmid: 17593246
references.citation: J Bacteriol. 1992 Jan;174(1):84-91
references.pmid: 1729227
references.citation: Proc Natl Acad Sci U S A. 2002 Nov 26;99(24):15705-10
references.pmid: 12441401
references.citation: Future Microbiol. 2012 Jun;7(6):685-703
references.pmid: 22702524
references.citation: Cell. 2012 Jun 22;149(7):1578-93
references.pmid: 22726443
references.citation: Trends Microbiol. 1997 Sep;5(9):360-3
references.pmid: 9294892
references.citation: J Bacteriol. 2010 Jan;192(1):29-37
references.pmid: 19820103
references.citation: Infect Immun. 2014 Jan;82(1):174-83
references.pmid: 24126528
references.citation: J Biol Chem. 2004 Aug 13;279(33):34631-42
references.pmid: 15169785
references.citation: J Bacteriol. 2003 Feb;185(3):991-1000
references.pmid: 12533475
references.citation: PLoS Pathog. 2005 Nov;1(3):e32
references.pmid: 16304611
references.citation: PLoS Pathog. 2006 Feb;2(2):e11
references.pmid: 16518469
references.citation: Cell Microbiol. 2011 Oct;13(10):1497-517
references.pmid: 21679290
references.citation: BMC Bioinformatics. 2010 Oct 15;11 Suppl 7:S4
references.pmid: 21106126
references.citation: BMC Bioinformatics. 2011 Nov 14;12:442
references.pmid: 22078363
references.citation: Mol Microbiol. 2000 Jun;36(5):997-1005
references.pmid: 10844685
references.citation: Science. 2011 Mar 4;331(6021):1147-8
references.pmid: 21385706
references.citation: Infect Immun. 2002 Jun;70(6):3264-70
references.pmid: 12011022
references.citation: J Clin Invest. 1992 Sep;90(3):953-64
references.pmid: 1522243
references.citation: Microbiology (Reading). 2006 Nov;152(Pt 11):3411-3424
references.pmid: 17074910
references.citation: Adv Exp Med Biol. 1999;473:261-74
references.pmid: 10659367
references.citation: J Bacteriol. 1998 Mar;180(5):1185-93
references.pmid: 9495757
references.citation: J Bacteriol. 2001 Oct;183(19):5733-42
references.pmid: 11544237
references.citation: Mol Microbiol. 2000 May;36(3):749-61
references.pmid: 10844662
references.citation: Biochim Biophys Acta. 2004 Nov 11;1694(1-3):207-17
references.pmid: 15546667
references.citation: Nat Methods. 2010 Apr;7(4):325-30
references.pmid: 20228815
references.citation: Mol Microbiol. 2005 Jul;57(1):85-96
references.pmid: 15948951
references.citation: Infect Immun. 2005 Jan;73(1):146-54
references.pmid: 15618149
references.citation: Mol Microbiol. 1997 May;24(4):747-56
references.pmid: 9194702
references.citation: Infect Immun. 1996 Dec;64(12):5410-2
references.pmid: 8945597
references.citation: Infect Immun. 1995 Oct;63(10):4024-8
references.pmid: 7558314
references.citation: mBio. 2012 Jun 12;3(3):
references.pmid: 22691391
references.citation: Mol Microbiol. 1996 Oct;22(2):327-38
references.pmid: 8930917
references.citation: J Biol Chem. 2012 Sep 7;287(37):31148-54
references.pmid: 22810232
references.citation: Curr Opin Microbiol. 2011 Apr;14(2):188-93
references.pmid: 21353625
references.citation: Infect Immun. 2001 Jan;69(1):367-77
references.pmid: 11119526
references.citation: Curr Opin Microbiol. 2009 Feb;12(1):117-24
references.pmid: 19157959
references.citation: Infect Immun. 1994 Oct;62(10):4641-5
references.pmid: 7927733
references.citation: Gene. 1997 Jun 11;192(1):51-9
references.pmid: 9224874
references.citation: Infect Immun. 2011 Jun;79(6):2182-92
references.pmid: 21464085
references.citation: Infect Immun. 2005 Dec;73(12):7817-26
references.pmid: 16299271
references.citation: J Bacteriol. 2000 Feb;182(3):771-81
references.pmid: 10633113
references.citation: PLoS One. 2008 Jul 30;3(7):e2826
references.pmid: 18665275
references.citation: Microbiology (Reading). 2008 Jun;154(Pt 6):1570-1583
references.pmid: 18524912