Evidence that the N-terminal region of the Vibrio fischeri LuxR protein constitutes an autoinducer-binding domain.
The Vibrio fischeri luminescence genes are regulated by the LuxR protein and an N-acyl homoserine lactone compound termed the autoinducer. The C-terminal one-third of LuxR contains a domain that can interact with the transcription complex and activate the luminescence genes. On the basis of limited evidence it has been suggested that the N-terminal two-thirds of LuxR constitutes a domain that serves to bind the autoinducer. We show that tritium-labeled autoinducer binds to Escherichia coli cells in which LuxR is overexpressed. We also show that tritium-labeled autoinducer binds to E. coli in which truncated LuxR proteins missing portions of the C-terminal domain are expressed but does not bind to E. coli cells in which truncated LuxR proteins missing portions of the N-terminal region are expressed. Our results provide evidence that the autoinducer binds to LuxR and that in E. coli the N-terminal two-thirds of LuxR can fold into a polypeptide capable of binding the autoinducer in the absence of the C-terminal domain.
Department of Microbiology, University of Iowa, Iowa City 52242.
B L
BL
Hanzelka
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EP
Greenberg
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D018834:Chaperonin 60 / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D012097:Repressor Proteins; D013329:Structure-Activity Relationship; D015534:Trans-Activators; D014733:Vibrio / Q000378:metabolism*
D001426:Bacterial Proteins; D018834:Chaperonin 60; D012097:Repressor Proteins; D015534:Trans-Activators; C064778:LuxR autoinducer binding proteins; C030654:N-(3-oxohexanoyl)-3-aminodihydro-2(3H)-furanone; D015107:4-Butyrolactone