Sequence analysis of bacterial genomes revealed a novel DNA-binding domain. This domain is found in several response regulators of the two-component signal transduction system, such as Pseudomonas aeruginosa AlgR, involved in the regulation of alginate biosynthesis and in the pathogenesis of cystic fibrosis; Clostridium perfringens VirR, a regulator of virulence factors, and in several regulators of bacteriocin biosynthesis, previously unified in the AgrA/ComE family. Most of the transcriptional regulators that contain this DNA-binding domain are involved in biosynthesis of extracellular polysaccharides, fimbriation, expression of exoproteins, including toxins, and quorum sensing. We refer to it as the LytTR ('litter') domain, after Bacillus subtilis LytT and Staphylococcus aureus LytR response regulators, involved in regulation of cell autolysis. In addition to response regulators, the LytTR domain is found in combination with MHYT, PAS and other sensor domains.