Functionalized Proline-Rich Peptides Bind the Bacterial Second Messenger c-di-GMP

C-di-GMP is an attractive target in the fight against bacterial infections as it is a near ubiquitous second messenger that regulates important cellular processes, including biofilm formation and virulence of pathogens. The screening of a combinatorial peptide library enabled the identification of the proline-rich tetrapeptide Gup-Gup-Nap-Arg that binds C-di-GMP in water with selectivity over other nucleotides. Computational and CD spectroscopic studies provided a binding mode of the complex and enabled the design of a pentapeptide with even higher binding strength towards C-di-GMP. Biological studies showed that the tetrapeptide inhibits biofilm growth of the opportunistic pathogen P. aeruginosa.