biostudies-literatureUnknown183(2)Moreno AJMyxococcus xanthus responds to blue light by producing carotenoids. Several regulatory genes are known that participate in the light action mechanism, which leads to the transcriptional activation of the carotenoid genes. We had already reported the isolation of a carotenoid-less, Tn5-induced strain (MR508), whose mutant site was unlinked to the indicated regulatory genes. Here, we show that OmegaMR508::Tn5 affects all known light-inducible promoters in different ways. It blocks the activation of two of them by light but makes the activity of a third one light independent. The OmegaMR508 locus has been cloned and sequenced. The mutation had occurred at the promoter of a gene we propose is the M. xanthus ortholog of ihfA. This encodes the alpha subunit of the histone-like integration host fJournal of bacteriology557-69https://www.ebi.ac.uk/biostudies/studies/S-EPMC94911biostudies-literatureihfA gene of the bacterium Myxococcus xanthus and its role in activation of carotenoid genes by blue light.PMC94911Murillo FJFontes MMoreno AJfalseihfA gene of the bacterium Myxococcus xanthus and its role in activation of carotenoid genes by blue light.Myxococcus xanthus responds to blue light by producing carotenoids. Several regulatory genes are known that participate in the light action mechanism, which leads to the transcriptional activation of the carotenoid genes. We had already reported the isolation of a carotenoid-less, Tn5-induced strain (MR508), whose mutant site was unlinked to the indicated regulatory genes. Here, we show that OmegaMR508::Tn5 affects all known light-inducible promoters in different ways. It blocks the activation of two of them by light but makes the activity of a third one light independent. The OmegaMR508 locus has been cloned and sequenced. The mutation had occurred at the promoter of a gene we propose is the M. xanthus ortholog of ihfA. This encodes the alpha subunit of the histone-like integration host f2001-01-01T00:00:00Z2001 Jan2025-04-04T10:52:47.335Z2019-03-27T00:16:43ZS-EPMC949111113394910.1128/JB.183.2.557-569.200110.1128/jb.183.2.557-569.2001