Determination of structural elements related to the biological activities of a potent decapeptide agonist of human C5a anaphylatoxin

Abstract

The structural features related to the biologic activities of a potent, response-selective decapeptide agonist of human C5a, YSFKPMPLaR (C5a65-74, Y65, F67, P69, P71, D-Ala73), were identified by NMR analysis in H2O, DMSO and TFE. This investigation showed that the KPM residues in H2O and the SFKPM residues in DMSO exhibited an extended backbone conformation, whereas a twisted conformation was found in this region in TFE. In H2O, the C-terminal region (PLaR) adopted a distorted type II beta-turn or a type II/V beta-turn. In the type IIN beta-turn, Leu72 exhibited a conformation typical of a type II beta-turn, whereas D-Ala73 exhibited a conformation characteristic of a type V beta-turn. Furthermore, a gamma-turn involving residues LaR overlapped with the type II/V beta-turn. In DMSO, the C-terminal region had the analogous turn-like motif (type II/V beta-turn overlapping with gamma-turn) found in H2O. In TFE, no beta-turn motifs were formed by the PLaR residues. These turn-like motifs in the C-terminal region of the peptide in both H2O and DMSO were in agreement with the biologically important conformations predicted earlier by a structure-function analysis of a related panel of decapeptide analogs. The motifs determined by the NMR analysis of YSFKPMPLaR in H2O and DMSO may represent structural elements important for C5a agonist activity and thus can be used to design the next generation of C5a agonist, partial agonist and antagonist analogs.

Development of Response-Selective Agonists of Human C5a Anaphylatoxin Conformational, Biological, and Therapeutic Considerations

“…THERAPEUTIC USES OF A CONFORMATIONALLY BIASED RESPONSE-SELECTIVE AGONIST OF C5A: YSFKPMPLaR AS A MOLECULAR ADJUVANT NMR analysis [49] of YSFKPMPLaR in water indicated the presence of extended, polyproline II (P II ) backbone conformation extending through residues 68-70/71 (KPM/P), which was expected from the presence of the Pro at position 69. The C-terminal region (PLaR) adopted a distorted type II β-turn or a type II/V β-turn.…”

A conformationally-biased, response-selective agonist of C5a acts as a molecular adjuvant by modulating antigen processing and presentation activities of human dendritic cells

“…However, we have developed a conformationally-biased, responseselective, decapeptide agonist of C5a, C5a 65-74 Y65,F67,P69, P71,D-Ala-73 (YSFKPMPLaR or EP54) that retains C5a-like immune stimulatory properties at the expense of C5a-like inflammatory properties via the engagement of neutrophils [10][11][12][13]. This bio-selectivity results from the unique conformational features expressed by EP54, which are well accommodated by C5a receptors (C5aR) expressed on antigen presenting cells such as DCs and macrophages, but not by C5aRs on neutrophils [14,15]. These conformational features also render EP54 stable to proteolysis by serum carboxypeptidases [16].…”

International Union of Basic and Clinical Pharmacology. LXXXVII. Complement Peptide C5a, C4a, and C3a Receptors

“…EP-54 (Tyr-Ser-Phe-Lys-Pro-MetPro-Leu-DAla-Arg) is an agonist at both the C5a 1 receptor and C3a receptor but has little or no activity at the second C5a receptor C5a 2 receptor (also known as C5R2, C5L2, GPR77) . In contrast, EP-67 (Tyr-Ser-Phe-Lys-Asp-Met-Pro-(Me)Leu-DAlaArg) is a weak agonist at both the C5a 1 receptor and the C3a receptor but may have greater activity at the C5a 2 receptor (Kawatsu et al, 1996;Short et al, 1999;Taylor et al, 2001;Vogen et al, 1999aVogen et al, , 1999b.…”