FIG. 5.

Cluster analysis of DcuS and CitA homologs. Sequences were identified on the basis of their similarities to the DcuS and CitA periplasmic domains, as described in Materials and Methods. The clusters are labeled according to the main putative activity of their members, but most clusters do not consist exclusively of one type. Most strikingly, the chemoreceptor cluster has two subclusters of chemoreceptors and one (cyan) made up mainly of histidine kinases and some diguanylate cyclases. The cluster containing DcuS and CitA was reclustered at a more stringent cutoff in order to separate the two groups.