<p>The bacterium <taxon tax_id="34">Myxococcus xanthus</taxon> responds to blue light by producing carotenoids. It also responds to starvation conditions by developing fruiting bodies, where the cells differentiate into myxospores. Each response entails the transcriptional activation of a separate set of genes. A single gene, carD, is required for the activation of both light- and starvation-inducible genes [<cite idref="PUB00008194"/>].</p><p>The predicted protein contains four repeats of a DNA-binding domain present in mammalian high mobility group I(Y) proteins and other nuclear proteins from animals and plants. Other peptide stretches on CarD also resemble functional domains typical of eukaryotic transcription factors, including a very acidic region and a leucine zipper. High mobility group yI(Y) proteins are known to bind the minor groove of A+T-rich DNA [<cite idref="PUB00008194"/>].</p> Transcription factor CarD