Light-induced carotenogenesis in Myxococcus xanthus functional characterization of the ECF sigma factor CarQ and antisigma factor CarR

Douglas F Browning, David E Whitworth, David A Hodgson

Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

67 Dyfyniadau (Scopus)

Crynodeb

Illumination of dark-grown Myxococcus xanthus with blue light leads to the induction of carotenoid synthesis. Central to this response is the activation of the light-inducible promoter, PcarQRS, and the transcription of three downstream genes, carQ, carR and carS. Sequence analysis predicted that CarQ is a member of the ECF (extracytoplasmic function) subfamily of RNA polymerase sigma factors, and that CarR is an inner membrane protein. Genetic analysis strongly implied that CarR is an antisigma factor that sequesters CarQ in a transcriptionally inactive complex. Using in vitro transcription run-off assays, we present biochemical evidence that CarQ functions as a bacterial sigma factor and is responsible for transcription initiation at PcarQRS. Similar experiments using the crtI promoter failed to implicate CarQ in direct transcription of the crtI gene. Experiments using the yeast two-hybrid system demonstrated a protein-protein interaction between CarQ and CarR, providing evidence of a CarQ-CarR complex. The yeast two-hybrid system data also indicated that CarR is capable of oligomerization. Fractionation of M. xanthus membranes with the detergent sarkosyl showed that CarR was associated with the inner membrane. Furthermore, CarR was found to be unstable in illuminated stationary phase cells, providing a possible mechanism by which the CarR-CarQ complex is disrupted.
Iaith wreiddiolSaesneg
Tudalennau (o-i)237-251
Nifer y tudalennau15
CyfnodolynMolecular Microbiology
Cyfrol48
Rhif cyhoeddi1
Dyddiad ar-lein cynnar25 Maw 2003
Dynodwyr Gwrthrych Digidol (DOIs)
StatwsCyhoeddwyd - Ebr 2003

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