期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1987
卷号：84
期号：8
页码：2359-2362
DOI：10.1073/pnas.84.8.2359
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The synthesis of carotenoids by Myxococcus xanthus requires illumination with blue light. Mutations at two loci (carA and carR) remove the blue-light requirement and cause constitutive production of carotenoids. Mutations at a different locus (carB) prevent carotenogenesis in both wild-type and constitutive mutant strains. We describe here three independent car mutations induced by insertion of Tn5 lac, a transposon that carries a transcriptional probe for exogenous promoters. All three transposon insertions block carotenogenesis even in constitutive mutant strains. One insertion is in a previously unknown car gene and the other two are in the carB locus. One of the carB insertions expresses {beta}-galactosidase at very low levels in the dark but is strongly activated by light. When this Tn5 lac insertion is introduced in carA or carR mutants it expresses {beta}-galactosidase in dark- as well as light-grown cells. We conclude that carotenogenesis in M. xanthus is activated at the level of transcription by a light-induced mechanism in which the carA and the carR loci (or their gene products) take part. The potential usefulness of M. xanthus as a simple and sensitive tool for studies in photobiology is discussed.
