FIG. 1.

Schematic illustration of cyaC in the wild type (WT) and cyaC mutants C1068, C3212, and H1. The positions and orientations of npt (neomycin phosphotransferase gene) and the transposon (Tn5-1063) are indicated by triangles. Domain abbreviations: RR, response regulator-like domain; GAF, GAF-like domain; HK, histidine kinase-like domain; AC, adenylate cyclase-like domain. The figure is not drawn to scale. GAF domains are part of a large superfamily of proteins that bind diverse ligands and regulate the biochemical output of proteins in which they are found (2, 4, 38, 40). GAF domains appear to represent sensor domains which receive a signal that is subsequently transmitted to the catalytic domain via the response regulator domain.