FIG 4.

Scheme of NbdA activation. Possible mechanism of NO-induced biofilm dispersal via the MHYT domain-containing NbdA protein. This protein is composed of three domains, a membrane-spanning MHYT domain, a degenerated GGDEF domain, and a PDE-EAL domain. Binding of NO is supposed to occur via copper ions (Cu) located in the MHYT domain. The signal is then transmitted via the GGDEF domain to the EAL domain, triggering its PDE activity and, thus, c-di-GMP hydrolysis to pGpG. GTP may increase the PDE activity of the EAL domain by binding to the degenerated GGDEF. In parallel, NO may also activate the transcription of NbdA by a yet-unknown mechanism.