FIG. 6.
Proposed domain structure of the PDEA and DGC isoenzymes of A. xylinum. The GGDEF and EAL domains form a motif conserved among all six isoenzymes. N-terminal regions putatively function in oxygen sensing (OS). Predicted sites of GTP binding may indicate catalytic sites of DGC proteins. TM, putative transmembrane helices; aa, amino acids.