title: Probing the ArcA regulon under aerobic/ROS conditions in Salmonella enterica serovar Typhimurium.
abstract: BACKGROUND
  Hydrogen peroxide (H₂O₂) is a reactive oxygen species (ROS), which is part of the oxidative burst encountered upon internalization of Salmonella enterica serovar Typhimurium (S. Typhimurium) by phagocytic cells. It has previously been established that, the ArcAB two-component system plays a critical role in ROS resistance, but the genes regulated by the system remained undetermined to date. We therefore investigated the ArcA regulon in aerobically growing S. Typhimurium before and after exposure to H₂O₂ by querying gene expression and other physiological changes in wild type and ΔarcA strains.
  
  
  RESULTS
  In the ΔarcA strain, expression of 292 genes showed direct or indirect regulation by ArcA in response to H₂O₂, of which 141were also regulated in aerobiosis, but in the opposite direction. Gene set enrichment analysis (GSEA) of the expression data from WT and ΔarcA strains, revealed that, in response to H₂O₂ challenge in aerobically grown cells, ArcA down regulated multiple PEP-PTS and ABC transporters, while up regulating genes involved in glutathione and glycerolipid metabolism and nucleotide transport. Further biochemical analysis guided by GSEA results showed that deletion of arcA during aerobic growth lead to increased reactive oxygen species (ROS) production which was concomitant with an increased NADH/NAD+ ratio. In absence of ArcA under aerobic conditions, H₂O₂ exposure resulted in lower levels of glutathione reductase activity, leading to a decreased GSH (reduced glutathione)/GSSG (oxidized glutathione) ratio.
  
  
  CONCLUSIONS
  The ArcA regulon was defined in 2 conditions, aerobic growth and the combination of peroxide treatment and aerobic growth in S. Typhimurium. ArcA coordinates a response that involves multiple aspects of the carbon flux through central metabolism, which ultimately modulates the reducing potential of the cell.
authors.affiliation: Laboratorio de Microbiología Molecular, Facultad Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile. csaavedra@unab.cl.
authors.forename: Eduardo H
authors.initials: EH
authors.lastname: Morales
authors.forename: Bernardo
authors.initials: B
authors.lastname: Collao
authors.forename: Prerak T
authors.initials: PT
authors.lastname: Desai
authors.forename: Iván L
authors.initials: IL
authors.lastname: Calderón
authors.forename: Fernando
authors.initials: F
authors.lastname: Gil
authors.forename: Roberto
authors.initials: R
authors.lastname: Luraschi
authors.forename: Steffen
authors.initials: S
authors.lastname: Porwollik
authors.forename: Michael
authors.initials: M
authors.lastname: McClelland
authors.forename: Claudia P
authors.initials: CP
authors.lastname: Saavedra
mesh_terms: D000332:Aerobiosis; D015964:Gene Expression Regulation, Bacterial; D006861:Hydrogen Peroxide / Q000378:metabolism*; D018085:Regulon; D012486:Salmonella typhimurium / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome
chemical_list: D006861:Hydrogen Peroxide
references.citation: FEMS Microbiol Lett. 1996 Feb 15;136(2):215-20
references.pmid: 8869506
references.citation: BMC Genomics. 2008 Jan 25;9:42
references.pmid: 18221523
references.citation: J Biol Chem. 1997 Jun 20;272(25):15661-7
references.pmid: 9188456
references.citation: J Biol Chem. 1991 Apr 15;266(11):6957-65
references.pmid: 1849898
references.citation: BMC Microbiol. 2011 Mar 21;11:58
references.pmid: 21418628
references.citation: Annu Rev Microbiol. 2003;57:395-418
references.pmid: 14527285
references.citation: BMC Microbiol. 2009 Aug 28;9:183
references.pmid: 19715602
references.citation: FASEB J. 1989 Dec;3(14):2574-82
references.pmid: 2556311
references.citation: Proc Natl Acad Sci U S A. 2001 Dec 18;98(26):15264-9
references.pmid: 11742086
references.citation: PLoS Pathog. 2009 Jul;5(7):e1000477
references.pmid: 19578432
references.citation: Infect Immun. 2002 Feb;70(2):451-61
references.pmid: 11796570
references.citation: J Bacteriol. 2010 Mar;192(6):1735-9
references.pmid: 20097862
references.citation: Microbiology (Reading). 2009 Sep;155(Pt 9):2919-2929
references.pmid: 19542004
references.citation: BMC Microbiol. 2012 May 22;12:63
references.pmid: 22545862
references.citation: Microbes Infect. 2003 May;5(6):527-34
references.pmid: 12758282
references.citation: Cell. 1985 Jul;41(3):753-62
references.pmid: 2988786
references.citation: J Bacteriol. 2003 Jan;185(1):204-9
references.pmid: 12486057
references.citation: Free Radic Biol Med. 1998 Mar 1;24(4):556-62
references.pmid: 9559867
references.citation: J Bacteriol. 2010 Feb;192(3):746-54
references.pmid: 19933363
references.citation: Mol Microbiol. 2007 Jun;64(5):1375-90
references.pmid: 17542927
references.citation: Science. 2001 Jun 22;292(5525):2314-6
references.pmid: 11423658
references.citation: Mol Cell Biochem. 1987 Jan;73(1):61-8
references.pmid: 3543652
references.citation: J Bacteriol. 1996 Nov;178(21):6238-49
references.pmid: 8892825
references.citation: Appl Environ Microbiol. 2006 Apr;72(4):2586-93
references.pmid: 16597961
references.citation: Mol Microbiol. 1991 Feb;5(2):455-65
references.pmid: 2041478
references.citation: J Biol Chem. 2005 Apr 15;280(15):15084-96
references.pmid: 15699038
references.citation: J Biol Chem. 2001 May 25;276(21):18031-7
references.pmid: 11278973
references.citation: Biotechniques. 2003 Feb;34(2):374-8
references.pmid: 12613259
references.citation: Mol Microbiol. 2011 Apr;80(2):319-34
references.pmid: 21338418
references.citation: J Biol Chem. 2011 Mar 25;286(12):10147-54
references.pmid: 21252224
references.citation: J Biol Chem. 2010 Nov 19;285(47):36785-93
references.pmid: 20851888
references.citation: J Bacteriol. 2009 Jul;191(14):4605-14
references.pmid: 19447905
references.citation: Proc Natl Acad Sci U S A. 2004 Sep 7;101(36):13318-23
references.pmid: 15326287
references.citation: Bioinformatics. 2009 Sep 15;25(18):2425-9
references.pmid: 19602526
references.citation: Biochem Biophys Res Commun. 2010 Aug 6;398(4):690-4
references.pmid: 20621065
references.citation: J Bacteriol. 2010 Jan;192(2):560-7
references.pmid: 19897643
references.citation: J Exp Med. 1966 Oct 1;124(4):573-83
references.pmid: 5922285
references.citation: Mol Microbiol. 2002 Oct;46(1):281-91
references.pmid: 12366850
references.citation: Mol Microbiol. 2010 Mar;75(6):1389-401
references.pmid: 20149100
references.citation: J Bacteriol. 1992 Sep;174(17):5617-23
references.pmid: 1512197
references.citation: Proc Natl Acad Sci U S A. 2005 Oct 25;102(43):15545-50
references.pmid: 16199517
references.citation: Annu Rev Microbiol. 2000;54:439-61
references.pmid: 11018134
references.citation: Science. 1978 Sep 8;201(4359):875-80
references.pmid: 210504
references.citation: Res Microbiol. 2011 Feb-Mar;162(2):214-22
references.pmid: 21144897
references.citation: Nucleic Acids Res. 2001 May 1;29(9):e45
references.pmid: 11328886
references.citation: J Bacteriol. 2000 Jul;182(13):3858-62
references.pmid: 10851007
references.citation: Mol Microbiol. 1990 May;4(5):715-27
references.pmid: 2201868
references.citation: J Bacteriol. 2006 Nov;188(22):7853-61
references.pmid: 16980468
references.citation: J Biol Chem. 1999 Apr 9;274(15):10119-28
references.pmid: 10187794
references.citation: Nat Protoc. 2008;3(10):1578-88
references.pmid: 18802439
references.citation: J Bacteriol. 1997 Sep;179(17):5429-35
references.pmid: 9286997
references.citation: J Bacteriol. 2000 Oct;182(20):5749-56
references.pmid: 11004173
references.citation: Nucleic Acids Res. 2008 Sep;36(15):4863-71
references.pmid: 18653527
references.citation: J Biol Chem. 2001 Nov 2;276(44):40873-9
references.pmid: 11527965
references.citation: Mol Microbiol. 1996 Feb;19(4):777-90
references.pmid: 8820648
references.citation: J Bacteriol. 2005 May;187(9):3171-9
references.pmid: 15838044
references.citation: J Biol Chem. 2004 Mar 26;279(13):12588-97
references.pmid: 14711822
references.citation: J Biol Chem. 2003 Aug 8;278(32):30193-8
references.pmid: 12783863