Fig. 2: CdbA has a RHH fold.

a CdbA dimer with monomers in red and green. Residues discussed in text are indicated. b CdbA tetramer with individual monomers in red, green, yellow, and blue. Residues important for tetramer formation are indicated. c Electrostatic surface potential of CdbA. The electrostatic potential ranges from −5 (red) to +5 (blue) kT/e. The view of CdbA is as in b. d Model for DNA binding by CdbA. Left panel, CdbA dimer interacting with DNA with the two interfaces identified by HDX to be involved in c-di-GMP binding colored in red and green (see also Fig. 3e); middle panel, Arc tetramer bound to DNA (1BDT41); right panel, overlay of Arc tetramer bound to DNA and CdbA tetramer.