Binding of peptides in solution by the Escherichia coli chaperone PapD as revealed using an inhibition ELISA and NMR spectroscopy

PapD is the prototype member of a family of periplasmic chaperones which ar e required for assembly of virulence associated pill in pathogenic, gram-ne gative bacteria. In the present investigation, an ELISA has been developed for evaluation of compounds as inhibitors of PapD. Synthetic peptides, incl uding an octamer, derived from the C-terminus of the pilus adhesin PapG wer e able to inhibit PapD in the ELISA. Evaluation of a panel of octapeptides in the ELISA, in combination with NMR studies, showed that the peptides wer e bound as extended beta-strands by PapD in aqueous solution. The PapD-pept ide complex was stabilized by backbone to backbone hydrogen bonds and inter actions involving three hydrophobic peptide side chains. This structural in formation, together with previous crystal structure data, provides a starti ng point in efforts to design and synthesize compounds which bind to chaper ones and interfere with pilus assembly in pathogenic bacteria. (C) 1998 Els evier Science Ltd. All rights reserved.