Pseudomonas aeruginosa autoinducer enters and functions in mammalian cells.
Quorum sensing (QS) is a cell density-dependent signaling mechanism used by many bacteria to control gene expression. Several recent reports indicate that the signaling molecules (autoinducers) that mediate QS in Pseudomonas aeruginosa may also modulate gene expression in host cells; however, the mechanisms are largely unknown. Here we show that two P. aeruginosa autoinducers, N-3-oxododecanoyl-homoserine lactone and N-butyryl-homoserine lactone, can both enter eukaryotic cells and activate artificial chimeric transcription factors based on their cognate transcriptional activators, LasR and RhlR, respectively. The autoinducers promoted nuclear localization of chimeric proteins containing the full LasR or RhlR coding region, and the LasR-based proteins were capable of activating transcription of a LasR-dependent luciferase gene. Responsiveness to autoinducer required the N-terminal autoinducer-binding domains of LasR and RhlR. Truncated proteins consisting of only the C-terminal helix-turn-helix DNA-binding domains of both proteins attached to a nuclear localization signal efficiently translocated to the nucleus in the absence of autoinducer, and truncated LasR-based proteins functioned as constitutively active transcription factors. Chimeric LasR proteins were only activated by their cognate autoinducer ligand and not by N-butyryl-L-homoserine lactone. These data provide evidence that autoinducer molecules from human pathogens can enter mammalian cells and suggest that autoinducers may influence gene expression in host cells by interacting with and activating as-yet-unidentified endogenous proteins.
Williams
Simon C
SC
Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA.
Patterson
Erin K
EK
Carty
Nancy L
NL
Griswold
John A
JA
Hamood
Abdul N
AN
Rumbaugh
Kendra P
KP
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006714:Homoserine / Q000031:analogs & derivatives* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C080365:LasR protein, Pseudomonas aeruginosa; C109860:N-(3-oxododecanoyl)homoserine lactone; C092312:N-butyrylhomoserine lactone; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C074896:rhiR protein, Rhizobium leguminosarum; D006714:Homoserine; D015107:4-Butyrolactone