title: A putative regulatory genetic locus modulates virulence in the pathogen Leptospira interrogans.
abstract: Limited research has been conducted on the role of transcriptional regulators in relation to virulence in Leptospira interrogans, the etiological agent of leptospirosis. Here, we identify an L. interrogans locus that encodes a sensor protein, an anti-sigma factor antagonist, and two genes encoding proteins of unknown function. Transposon insertion into the gene encoding the sensor protein led to dampened transcription of the other 3 genes in this locus. This lb139 insertion mutant (the lb139(-) mutant) displayed attenuated virulence in the hamster model of infection and reduced motility in vitro. Whole-transcriptome analyses using RNA sequencing revealed the downregulation of 115 genes and the upregulation of 28 genes, with an overrepresentation of gene products functioning in motility and signal transduction and numerous gene products with unknown functions, predicted to be localized to the extracellular space. Another significant finding encompassed suppressed expression of the majority of the genes previously demonstrated to be upregulated at physiological osmolarity, including the sphingomyelinase C precursor Sph2 and LigB. We provide insight into a possible requirement for transcriptional regulation as it relates to leptospiral virulence and suggest various biological processes that are affected due to the loss of native expression of this genetic locus.
authors.affiliation: Institut Pasteur, Biology of Spirochetes Unit, Paris, France.
authors.forename: Azad
authors.initials: A
authors.lastname: Eshghi
authors.forename: Jérôme
authors.initials: J
authors.lastname: Becam
authors.forename: Ambroise
authors.initials: A
authors.lastname: Lambert
authors.forename: Odile
authors.initials: O
authors.lastname: Sismeiro
authors.forename: Marie-Agnès
authors.initials: MA
authors.lastname: Dillies
authors.forename: Bernd
authors.initials: B
authors.lastname: Jagla
authors.forename: Elsio A
authors.initials: EA
authors.lastname: Wunder
authors.forename: Albert I
authors.initials: AI
authors.lastname: Ko
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Coppee
authors.forename: Cyrille
authors.initials: C
authors.lastname: Goarant
authors.forename: Mathieu
authors.initials: M
authors.lastname: Picardeau
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002465:Cell Movement / Q000502:physiology; D006224:Cricetinae; D004195:Disease Models, Animal; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D007668:Kidney / Q000382:microbiology; D007921:Leptospira interrogans / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D016254:Mutagenesis, Insertional; D017422:Sequence Analysis, DNA; D014774:Virulence / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins