title: Molybdate transporter ModABC is important for Pseudomonas aeruginosa chronic lung infection.
abstract: BACKGROUND
  Mechanisms underlying the success of Pseudomonas aeruginosa in chronic lung infection among cystic fibrosis (CF) patients are poorly defined. The modA gene was previously linked to in vivo competitiveness of P. aeruginosa by a genetic screening in the rat lung. This gene encodes a subunit of transporter ModABC, which is responsible for extracellular uptake of molybdate. This compound is essential for molybdoenzymes, including nitrate reductases. Since anaerobic growth conditions are known to occur during CF chronic lung infection, inactivation of a molybdate transporter could inhibit proliferation through the inactivation of denitrification enzymes. Hence, we performed phenotypic characterization of a modA mutant strain obtained by signature-tagged mutagenesis (STM_modA) and assessed its virulence in vivo with two host models.
  
  
  RESULTS
  The STM_modA mutant was in fact defective for anaerobic growth and unable to use nitrates in the growth medium for anaerobic respiration. Bacterial growth and nitrate usage were restored when the medium was supplemented with molybdate. Most significantly, the mutant strain showed reduced virulence compared to wild-type strain PAO1 according to a competitive index in the rat model of chronic lung infection and a predation assay with Dictyostelium discoideum amoebae. As the latter took place in aerobic conditions, the in vivo impact of the mutation in modA appears to extend beyond its effect on anaerobic growth.
  
  
  CONCLUSIONS
  These results support the modABC-encoded transporter as important for the pathogenesis of P. aeruginosa, and suggest that enzymatic machinery implicated in anaerobic growth during chronic lung infection in CF merits further investigation as a potential target for therapeutic intervention.
authors.affiliation: Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada. simone.perinet@gmail.com.|Département de microbiologie-infectiologie-immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada. simone.perinet@gmail.com.
authors.forename: Simone
authors.initials: S
authors.lastname: Périnet
authors.affiliation: Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada. Julie.jeukens.1@ulaval.ca.|Département de microbiologie-infectiologie-immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada. Julie.jeukens.1@ulaval.ca.
authors.forename: Julie
authors.initials: J
authors.lastname: Jeukens
authors.affiliation: Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada. kukavica@fmed.ulaval.ca.|Département de microbiologie-infectiologie-immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada. kukavica@fmed.ulaval.ca.
authors.forename: Irena
authors.initials: I
authors.lastname: Kukavica-Ibrulj
authors.affiliation: Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada. myriam.ouellet10@gmail.com.|Département de biochimie, de microbiologie et de bio-informatique, Faculté des Sciences et de Génie, Université Laval, Québec, QC, Canada. myriam.ouellet10@gmail.com.|Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Quebec, QC, Canada. myriam.ouellet10@gmail.com.
authors.forename: Myriam M
authors.initials: MM
authors.lastname: Ouellet
authors.affiliation: Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada. Steve.Charette@bcm.ulaval.ca.|Département de biochimie, de microbiologie et de bio-informatique, Faculté des Sciences et de Génie, Université Laval, Québec, QC, Canada. Steve.Charette@bcm.ulaval.ca.|Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec (CRIUCPQ), Quebec, QC, Canada. Steve.Charette@bcm.ulaval.ca.
authors.forename: Steve J
authors.initials: SJ
authors.lastname: Charette
authors.affiliation: Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada. rclevesq@ibis.ulaval.ca.|Département de microbiologie-infectiologie-immunologie, Faculté de Médecine, Université Laval, Québec, QC, Canada. rclevesq@ibis.ulaval.ca.
authors.forename: Roger C
authors.initials: RC
authors.lastname: Levesque
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002908:Chronic Disease; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D017136:Ion Transport; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008982:Molybdenum / Q000378:metabolism; D016254:Mutagenesis, Insertional; D011014:Pneumonia / Q000382:microbiology* / Q000473:pathology; D011552:Pseudomonas Infections / Q000382:microbiology* / Q000473:pathology; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D011994:Recombinant Proteins; C044659:molybdate; D008982:Molybdenum