Backbone Cyclic Peptide Antagonists, Derived from the Insect Pheromone Biosynthesis Activating Neuropeptide, Inhibit Sex Pheromone Biosynthesis in Moths

Miriam Altstein,Orna Ben-Aziz,Shai Daniel,Irit Schefler,Irina Zeltser,Chaim Gilon

doi:10.1074/jbc.274.25.17573

Abstract

We describe an application of the backbone cyclization and cycloscan concept for the design and synthesis of pheromone biosynthesis activating neuropeptide (PBAN) antagonists capable of inhibiting sex pheromone biosynthesis in Heliothis peltigera female moths. Two backbone cyclic (BBC) sub-libraries were designed and synthesized. The structure of the first sub-library ([Arg27]PBAN27-33NH2, termed the Ser sub-library) was based on the active C-terminal hexapeptide sequence (Tyr-Phe-Ser-Pro-Arg-Leu-NH2) of PBAN1-33NH2, which was found to comprise its active core. The second sub-library ([Arg27, D-Phe30]PBAN27-33NH2, termed the D-Phe sub-library) was based on the sequence of the lead antagonist Arg-Tyr-Phe-(D)Phe-Pro-Arg-Leu-NH2. In both sub-libraries the Pro residue was replaced by an Nalpha(omega-amino-alkyl)Gly building unit having various lengths of the alkyl chain. All the cyclic peptides in each sub-library had the same primary sequence and the same location of the ring. The members of each library differed from each other by the bridge size and bridge chemistry. Screening of the two libraries for pheromonotropic antagonists resulted in the disclosure of four compounds that fully inhibited sex pheromone biosynthesis at 1 nmol and were devoid of agonistic activity. All antagonistic peptides originated from the D-Phe sub-library. Substitution of the D-Phe30 amino acid with a Ser resulted in a loss of antagonistic activity. Agonistic activities were exhibited by peptides from both sub-libraries.

Highlights

It is well established that the activation of multiple receptors by the same peptide arises from the ability of a given peptide to exist in different interchangeable bioactive conformations [1]
In this study we present the application of sequence-biased cycloscan for the disclosure of small backbone cyclic (BBC) agonists and antagonists of the insect pheromone biosynthesis activating neuropeptide (PBAN) which regulates, among other functions, sex pheromone biosynthesis in female moths [12,13,14]
In this study we report the generation of highly potent, conformationally constrained BBC heptapeptide agonists and antagonists which fully inhibit one of the functions mediated by PBAN: sex pheromone biosynthesis in the female moth Heliothis peltigera

Summary

Introduction

It is well established that the activation of multiple receptors by the same peptide arises from the ability of a given peptide to exist in different interchangeable bioactive conformations [1]. These modes of cyclization involve modifications of side chains and ends which in many cases are essential for bioactivity, and their modification causes loss of activity These modes of cyclization are not sufficient to screen effectively the conformational space available for a linear peptide with a given sequence. To overcome these limitations, we have introduced two methods called backbone cyclization [2] and cycloscan [3]. The advantages of backbone cyclization over the naturally occurring modes of cyclization are because of the immense variability of spatial orientation of the constitute residues which result from the multiple anchoring points within a chain or between chains This allows us to screen the conformational space of a given peptide in an extremely efficient manner.

Methods

Results

Conclusion