Functional interplay between the Yersinia pseudotuberculosis YpsRI and YtbRI quorum sensing systems modulates swimming motility by controlling expression of flhDC and fliA.
Quorum sensing (QS) in Yersinia pseudotuberculosis involves two pairs of LuxRI orthologues (YpsRI and YtbRI) and multiple N-acylhomoserine lactones (AHLs). In a ypsI/ytbI mutant, AHL synthesis was abolished, unaffected in a ypsR/ytbR double mutant and substantially reduced in a ypsI/ytbR mutant, indicating that neither YpsR nor YtbR is essential for AHL synthesis. To determine the interrelationship between YpsRI and YtbRI we constructed chromosomal lux-promoter fusions to ypsR, ypsI, ytbR and ytbI and examined their expression in each of the QS mutant backgrounds. The YpsRI system negatively autoregulates itself but positively regulates the expression of the ytbRI system whereas the ytbRI system is positively autoregulated but only at the level of ytbI expression. YtbRI does not control expression of ypsR or ypsI. This hierarchical QS system controls swimming motility via regulation of flhDC and fliA. The AHLs synthesized via YtbI play a dual role, activating flhDC, in conjunction with YpsR but repressing fliA in conjunction with YtbR and YpsR. In liquid and plate assays, the early onset of motility observed in ypsR and ypsI mutants was abolished in ytbI, ytbR ypsI/ytbI, ypsR/ytbR mutants, indicating that QS regulates motility both positively (via YtbRI) and negatively (via YpsRI).
Atkinson
Steve
S
Institute of Infection, Immunity and Inflammation, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK.
Chang
Chien-Yi
CY
Patrick
Hannah L
HL
Buckley
Catherine M F
CM
Wang
Yao
Y
Sockett
R Elizabeth
RE
Cámara
Miguel
M
Williams
Paul
P
D054742:Acyl-Butyrolactones / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016384:Consensus Sequence; D003470:Culture Media / Q000032:analysis; D005407:Flagella / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D009876:Operon; D011401:Promoter Regions, Genetic; D053038:Quorum Sensing; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015011:Yersinia pseudotuberculosis / Q000235:genetics / Q000502:physiology*
D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; D003470:Culture Media; C064971:FliA protein, Bacteria; C085427:LuxI protein, Bacteria; D012097:Repressor Proteins; D012808:Sigma Factor; D015534:Trans-Activators; D014157:Transcription Factors; C064778:LuxR autoinducer binding proteins