Mono- and dibasic proteolytic cleavage sites in insect neuroendocrine peptide precursors

Abstract

Regulatory peptides are synthesized as part of larger precursors that are subsequently processed into the active substances. After cleavage of the signal peptide, further proteolytic processing occurs predominantly at basic amino acid residues. Rules have been proposed in order to predict which putative proteolytic processing sites are actually used, but these rules have been established for vertebrate peptide precursors and it is unclear whether they are also valid for insects. The aim of this paper is to establish the validity of these rules to predict proteolytic cleavage sites at basic amino acids in insect neuropeptide precursors. Rules describing the cleavage of mono‐ and dibasic potential processing sites in insect neuropeptide precursors are summarized below. Lys‐Arg pairs not followed by an aliphatic or basic amino acid residue are virtually always cleaved in insect regulatory peptide precursors, but cleavages of Lys‐Arg pairs followed by either an aliphatic or a basic amino acid residue are ambiguous, as is processing at Arg‐Arg pairs. Processing at Arg‐Lys pairs has so far not been demonstrated in insects and processing at Lys‐Lys pairs appears very rare. Processing at single Arg residues occurs only when there is a basic amino acid residue in position ‐4, ‐6, or ‐8, usually an Arg, but Lys or His residues work also. Although the current number of such sites is too limited to draw definitive conclusions, it seems plausible that cleavage at these sites is inhibited by the presence of aliphatic residues in the +1 position. However, cleavage at single Arg residues is ambiguous. When several potential cleavage sites overlap the one most easily cleaved appears to be processed. It cannot be excluded that some of the rules formulated here will prove less than universal, as only a limited number of cleavage sites have so far been identified. It is likely that, as in vertebrates, ambiguous processing sites exist to allow differential cleavage of the same precursor by different convertases and it seems possible that the precursors of allatostatins and PBAN are differentially cleaved in different cell types. Arch. Insect Biochem. Physiol. 43:49–63, 2000. © 2000 Wiley‐Liss, Inc.

Cardioacceleratory function of the neurohormone CCAP in the mosquito Anopheles gambiae

“…The ORF encodes a 25aa signal peptide, the CCAP peptide and multiple putative cleavage sites composed of dibasic amino acid residues (Veenstra, 2000). Based on empirical and bioinformatic experiments detailed in previously published work (Stangier et al, 1987;Cheung et al, 1992;Veenstra, 2000), cleavage from the signal peptide is followed by cleavage at the KR and KKR sequences that flank the CCAP peptide, yielding a sequence of H-PFCNAFTGCG.…”

Identification of SYWKQCAFNAVSCFamide: a broadly conserved crustacean C-type allatostatin-like peptide with both neuromodulatory and cardioactive properties

“…Signal peptide prediction was done via the online program SignalP 3.0, using both the Neural Networks and the Hidden Markov Models algorithms (Center for Biological Sequence Analysis, Technical University of Denmark, Lyngby, Denmark; http://www.cbs.dtu.dk/services/SignalP/ (Bendtsen et al, 2004). Prohormone convertase cleavage sites were predicted based on the information presented in Veenstra (Veenstra, 2000). Posttranslational modifications, e.g.…”

Peptidomic analysis of the larval Drosophila melanogaster central nervous system by two‐dimensional capillary liquid chromatography quadrupole time‐of‐flight mass spectrometry

“…Usually, the basic amino acids at the C-terminus of neuropeptides are removed by a carboxypeptidase E, found in the secretory pathway of neurosecretory cells. 58 …”