title: Characterization and analysis of the Burkholderia pseudomallei BsaN virulence regulon.
abstract: BACKGROUND
  Burkholderia pseudomallei is a facultative intracellular pathogen and the causative agent of melioidosis. A conserved type III secretion system (T3SS3) and type VI secretion system (T6SS1) are critical for intracellular survival and growth. The T3SS3 and T6SS1 genes are coordinately and hierarchically regulated by a TetR-type regulator, BspR. A central transcriptional regulator of the BspR regulatory cascade, BsaN, activates a subset of T3SS3 and T6SS1 loci.
  
  
  RESULTS
  To elucidate the scope of the BsaN regulon, we used RNAseq analysis to compare the transcriptomes of wild-type B. pseudomallei KHW and a bsaN deletion mutant. The 60 genes positively-regulated by BsaN include those that we had previously identified in addition to a polyketide biosynthesis locus and genes involved in amino acid biosynthesis. BsaN was also found to repress the transcription of 51 genes including flagellar motility loci and those encoding components of the T3SS3 apparatus. Using a promoter-lacZ fusion assay in E. coli, we show that BsaN together with the chaperone BicA directly control the expression of the T3SS3 translocon, effector and associated regulatory genes that are organized into at least five operons (BPSS1516-BPSS1552). Using a mutagenesis approach, a consensus regulatory motif in the promoter regions of BsaN-regulated genes was shown to be essential for transcriptional activation.
  
  
  CONCLUSIONS
  BsaN/BicA functions as a central regulator of key virulence clusters in B. pseudomallei within a more extensive network of genetic regulation. We propose that BsaN/BicA controls a gene expression program that facilitates the adaption and intracellular survival of the pathogen within eukaryotic hosts.
authors.forename: Yahua
authors.initials: Y
authors.lastname: Chen
authors.forename: Imke
authors.initials: I
authors.lastname: Schröder
authors.forename: Christopher T
authors.initials: CT
authors.lastname: French
authors.forename: Artur
authors.initials: A
authors.lastname: Jaroszewicz
authors.forename: Xiao Jie
authors.initials: XJ
authors.lastname: Yee
authors.forename: Boon-Eng
authors.initials: BE
authors.lastname: Teh
authors.forename: Isabelle J
authors.initials: IJ
authors.lastname: Toesca
authors.forename: Jeff F
authors.initials: JF
authors.lastname: Miller
authors.affiliation: Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore. yunn_hwen_gan@nuhs.edu.sg.
authors.forename: Yunn-Hwen
authors.initials: YH
authors.lastname: Gan
mesh_terms: D016957:Burkholderia pseudomallei / Q000235:genetics*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D018832:Molecular Chaperones / Q000378:metabolism; D005810:Multigene Family; D018085:Regulon; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism*
chemical_list: D018832:Molecular Chaperones; D014157:Transcription Factors; D037521:Virulence Factors
references.citation: J Bacteriol. 2000 Apr;182(8):2262-8
references.pmid: 10735870
references.citation: Angew Chem Int Ed Engl. 2009;48(26):4688-716
references.pmid: 19514004
references.citation: Trends Microbiol. 2013 Aug;21(8):430-41
references.pmid: 23870533
references.citation: Mol Microbiol. 2005 Apr;56(1):40-53
references.pmid: 15773977
references.citation: J Immunol. 2010 May 1;184(9):5160-71
references.pmid: 20335533
references.citation: Infect Immun. 2011 May;79(5):2079-88
references.pmid: 21402765
references.citation: Gene. 1994 Jul 22;145(1):69-73
references.pmid: 8045426
references.citation: Nat Methods. 2010 Sep;7(9):709-15
references.pmid: 20711195
references.citation: Bioinformatics. 1998;14(1):48-54
references.pmid: 9520501
references.citation: PLoS One. 2011 Mar 11;6(3):e17852
references.pmid: 21412437
references.citation: Microbiology (Reading). 2004 Aug;150(Pt 8):2669-2676
references.pmid: 15289563
references.citation: J Bacteriol. 1997 Apr;179(7):2116-25
references.pmid: 9079894
references.citation: J Mol Biol. 1996 Aug 16;261(2):209-21
references.pmid: 8757288
references.citation: Proc Natl Acad Sci U S A. 2004 Sep 28;101(39):14240-5
references.pmid: 15377794
references.citation: Infect Immun. 2002 Feb;70(2):504-11
references.pmid: 11796576
references.citation: Proc Natl Acad Sci U S A. 2002 May 14;99(10):7072-7
references.pmid: 11997446
references.citation: J Am Chem Soc. 2012 Aug 15;134(32):13192-5
references.pmid: 22765305
references.citation: Infect Immun. 2009 Apr;77(4):1636-48
references.pmid: 19168747
references.citation: Annu Rev Microbiol. 2010;64:495-517
references.pmid: 20528691
references.citation: Cell Microbiol. 2005 Oct;7(10):1447-58
references.pmid: 16153244
references.citation: Curr Top Microbiol Immunol. 2013;376:1-34
references.pmid: 23949285
references.citation: J Biol Chem. 1995 May 12;270(19):11181-9
references.pmid: 7538113
references.citation: Appl Environ Microbiol. 2002 Dec;68(12):5956-64
references.pmid: 12450816
references.citation: BMC Microbiol. 2010 Jan 29;10:28
references.pmid: 20109238
references.citation: Proc Int Conf Intell Syst Mol Biol. 1994;2:28-36
references.pmid: 7584402
references.citation: PLoS Genet. 2013;9(9):e1003795
references.pmid: 24068961
references.citation: Environ Microbiol. 2012 Aug;14(8):2058-70
references.pmid: 22176696
references.citation: Trans R Soc Trop Med Hyg. 2008 Dec;102 Suppl 1:S127-33
references.pmid: 19121674
references.citation: EMBO J. 2001 Apr 17;20(8):1850-62
references.pmid: 11296219
references.citation: Infect Immun. 2011 Aug;79(8):3064-73
references.pmid: 21670170
references.citation: FEMS Microbiol Lett. 2011 Oct;323(1):75-82
references.pmid: 22092682
references.citation: J Bacteriol. 2003 Aug;185(16):4992-6
references.pmid: 12897019
references.citation: Mol Microbiol. 2010 May;76(3):677-89
references.pmid: 20345664
references.citation: Philos Trans R Soc Lond B Biol Sci. 2012 Apr 19;367(1592):1102-11
references.pmid: 22411981
references.citation: FEMS Microbiol Lett. 2005 Jan 1;242(1):101-8
references.pmid: 15621426
references.citation: Infect Immun. 2011 Apr;79(4):1512-25
references.pmid: 21300775
references.citation: J Am Chem Soc. 2011 Feb 16;133(6):1638-41
references.pmid: 21247113
references.citation: Autophagy. 2008 Aug;4(6):744-53
references.pmid: 18483470
references.citation: J Microbiol. 2013 Aug;51(4):522-6
references.pmid: 23990305
references.citation: Proc Natl Acad Sci U S A. 1996 Jul 23;93(15):7794-9
references.pmid: 8755555
references.citation: Histopathology. 1995 Jan;26(1):51-5
references.pmid: 7713483
references.citation: Mol Microbiol. 2005 Oct;58(1):267-79
references.pmid: 16164564
references.citation: Cell Mol Life Sci. 2010 Apr;67(7):1065-75
references.pmid: 20043184
references.citation: Proc Natl Acad Sci U S A. 2011 Jul 19;108(29):12095-100
references.pmid: 21730143
references.citation: J Bacteriol. 2007 Dec;189(24):9044-9
references.pmid: 17933898
references.citation: BMC Microbiol. 2014 May 06;14:115
references.pmid: 24884837
references.citation: FEMS Microbiol Lett. 1992 Aug 15;74(2-3):271-6
references.pmid: 1526459
references.citation: Nat Rev Microbiol. 2006 Apr;4(4):272-82
references.pmid: 16541135
references.citation: Mol Microbiol. 2002 Nov;46(3):649-59
references.pmid: 12410823
references.citation: Methods. 2001 Dec;25(4):402-8
references.pmid: 11846609
references.citation: Infect Immun. 2000 Mar;68(3):1681-6
references.pmid: 10678988
references.citation: J Bacteriol. 2002 Aug;184(16):4409-19
references.pmid: 12142411
references.citation: Mol Microbiol. 1997 Aug;25(3):605-15
references.pmid: 9302022
references.citation: Cell Host Microbe. 2010 Jul 22;8(1):2-6
references.pmid: 20638635
references.citation: J Bacteriol. 2004 Jul;186(13):4056-66
references.pmid: 15205407
references.citation: Mol Microbiol. 2005 Jun;56(6):1627-35
references.pmid: 15916611