Probably catalyzes the synthesis of cyclic-di-GMP (c-di-GMP) via the condensation of 2 GTP molecules. Overexpression leads to a strong repression of swimming; swimming returns to normal when residues 359-360 are both mutated to Ala. Overexpression also leads to a 20-fold increase in c-di-GMP levels in vivo. Cyclic-di-GMP is a second messenger which controls cell surface-associated traits in bacteria. 2 GTP = cyclic di-3',5'-guanylate + 2 diphosphate Binds 1 Mg(2+) ion per monomer. Purine metabolism; 3',5'-cyclic di-GMP biosynthesis. Homodimer. CsrA binds to the mRNA and reduces its levels. Expressed at low levels at both 28 and 37 degrees Celsius. A slight increase in motility. No visible effect on curli production.