ASRAH: new family of small molecule-binding domains

The Anabaena sensory rhodopsin transducer is a small protein that is co-expressed with the bacterial sensory rhodopsin (ASR) and has been proposed to act as the transducer for this light-activated sensor. In a recent paper in Biology Direct we apply in-depth sequence and genome context analysis and demonstrate this protein is likely to bind small molecules, probably carbohydrates, and is also homologous to domains found in tandem in secreted proteins from several bacterial clades. We propose that the solo versions of this domain, whose homologs are usually associated with sugar-related enzymes, might represent a new kind of cytoplasmic sensor for sugars levels and, as such, regulate a diverse range of sugar metabolism operons and the light sensory behavior in Anabaena.