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A novel regulatory gene for light‐induced carotenoid synthesis in the bacterium Myxococcus xanthus
Author(s) -
Fontes Marta,
GalbisMartínez Lilian,
Murillo Francisco J.
Publication year - 2003
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2003.03319.x
Subject(s) - myxococcus xanthus , biology , mutant , gene , transposable element , phenotype , genetics , regulation of gene expression
Summary Myxococcus xanthuscells respond to blue light by producing carotenoids. Light triggers a network of regulatory actions that lead to the transcriptional activation of the carotenoid genes. By screening the colour phenotype of a collection of Tn5‐lacinsertion mutants, we have isolated a new mutant devoid of carotenoid synthesis. We map the transposon insertion, which co‐segregates with the mutant phenotype, to a previously unknown gene designated here ascarF. An in frame deletion withincarFcauses the same phenotype as the Tn5‐lacinsertion. ThecarFdeletion prevents the activation of the normally light‐inducible genes, without affecting the expression of any of the regulatory genes known to be expressed in a light‐independent manner. Until now, the switch that sets off the regulatory cascade had been identified with light‐driven inactivation of protein CarR, an antisigma factor. The exact mechanism of this inactivation has remained elusive. We show by epistatic analysis that thecarF gene product participates in the light‐dependent inactivation of CarR. The predicted CarF amino acid sequence reveals no known prokaryotic homologues. On the other hand, CarF is remarkably similar to Kua, a family of proteins of unknown function that is widely distributed among eukaryotes.