title: The high-mobility group A-type protein CarD of the bacterium Myxococcus xanthus as a transcription factor for several distinct vegetative genes.
abstract: CarD is the only reported prokaryotic protein showing structural and functional features typical of eukaryotic high-mobility group A transcription factors. In prokaryotes, proteins similar to CarD appear to be confined primarily to myxobacteria. In Myxococcus xanthus, CarD has been previously shown to act as a positive element in two different regulatory networks: one for light-induced synthesis of carotenoids and the other for starvation-induced fruiting body formation. We have now tested the effect of a loss-of-function mutation in the carD gene (carD1) on the expression of a random collection of lacZ-tagged genes, which are normally expressed in the dark during vegetative growth in rich medium. Our results indicate that CarD plays a significant role in the transcriptional regulation of various indicated genes. The carD1 mutation downregulates some genes and upregulates others. Also reported here is the isolation of several mutations that suppress the strong effect of carD1 on the expression of a particular vegetative gene. One of them (sud-2) also suppresses the effect of carD1 on other vegetative genes and on fruiting-body formation. Thus, CarD and the sud-2 gene product appear to participate in a single mechanism, which underlies various apparently diverse regulatory phenomena ascribed to CarD.
authors.affiliation: Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain.
authors.forename: Marisa
authors.initials: M
authors.lastname: Galbis-Martínez
authors.forename: Marta
authors.initials: M
authors.lastname: Fontes
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Murillo
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001435:Bacteriophages / Q000235:genetics; D005798:Genes, Bacterial; D005838:Genotype; D007700:Kinetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016941:Myxococcus xanthus / Q000235:genetics*; D010641:Phenotype; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C100589:CarD protein, Myxococcus xanthus; D015534:Trans-Activators