title: 4-Fluoroproline derivative peptides: effect on PPII conformation and SH3 affinity.
abstract: Eukaryotic signal transduction involves the assembly of transient protein-protein complexes mediated by modular interaction domains. Specific Pro-rich sequences with the consensus core motif PxxP adopt the PPII helix conformation upon binding to SH3 domains. For short Pro-rich peptides, little or no ordered secondary structure is usually observed before binding interactions. The association of a Pro-rich peptide with the SH3 domain involves unfavorable binding entropy due to the loss of rotational freedom on forming the PPII helix. With the aim of stabilizing the PPII helix conformation in the Pro-rich HPK1 decapeptide PPPLPPKPKF (P2), a series of P2 analogues was prepared, in which specific Pro positions were alternatively occupied by 4(S)- or 4(R)-4-fluoro-L-proline. The interactions of these peptides with the SH3 domain of the HPK1-binding partner HS1 were quantitatively analyzed by the NILIA-CD approach. A CD thermal analysis of the P2 analogues was performed to assess their propensity to adopt the PPII helix conformation. Contrary to our expectations, the K(d) values of the analogues were lower than that of the parent peptide P2. These results clearly show that the induction of a stable PPII helix conformation in short Pro-rich peptides is not sufficient to increase their affinity toward the SH3 domain and that the effect of 4-fluoroproline strongly depends on the position of this residue in the sequence and the chirality of the substituent in the pyrrolidine ring.
authors.affiliation: Institute of Biomolecular Chemistry, Padua Unit, CNR, Via Marzolo1, 35131 Padua, Italy. paolo.ruzza@unipd.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Ruzza
authors.forename: Giuliano
authors.initials: G
authors.lastname: Siligardi
authors.forename: Arianna
authors.initials: A
authors.lastname: Donella-Deana
authors.forename: Andrea
authors.initials: A
authors.lastname: Calderan
authors.forename: Rohanah
authors.initials: R
authors.lastname: Hussain
authors.forename: Chiara
authors.initials: C
authors.lastname: Rubini
authors.forename: Luca
authors.initials: L
authors.lastname: Cesaro
authors.forename: Alessio
authors.initials: A
authors.lastname: Osler
authors.forename: Andrea
authors.initials: A
authors.lastname: Guiotto
authors.forename: Lorenzo A
authors.initials: LA
authors.lastname: Pinna
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Borin
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015195:Drug Design; D066298:In Vitro Techniques; D007700:Kinetics; D051379:Mice; D008958:Models, Molecular; D046912:Multiprotein Complexes; D009842:Oligopeptides / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012996:Solutions; D014867:Water; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C094983:Hcls1 protein, mouse; D046912:Multiprotein Complexes; D009842:Oligopeptides; D010455:Peptides; D011993:Recombinant Fusion Proteins; D012996:Solutions; C431803:fluoro-proline; D014867:Water; C011083:polyproline; D011392:Proline; C102102:hematopoietic progenitor kinase 1; D017346:Protein Serine-Threonine Kinases