The primary structure of the Pol-RFamide neuropeptide precursor protein from the hydromedusa Polyorchis penicillatus indicates a novel processing proteinase activity

• Published in: Biochemical journal Vol. 299; no. 2; pp. 431 - 436
• Main Authors: SCHMUTZLER, C, DIEKHOFF, D, GRIMMELIKHUIJZEN, C. J. P
• Format: Journal Article
• Language: English
• Published: Colchester Portland Press 15-04-1994
• Subjects: Amino Acid Sequence; Aminoacids, peptides. Hormones. Neuropeptides; Analytical, structural and metabolic biochemistry; Animals; Base Sequence; Biological and medical sciences; Biological Evolution; Cnidaria - genetics; Cnidaria - metabolism; Endopeptidases - metabolism; Fundamental and applied biological sciences. Psychology; Gene Library; Insect Hormones - biosynthesis; Insect Hormones - chemistry; Molecular Sequence Data; Neuropeptides - biosynthesis; Neuropeptides - chemistry; Oligodeoxyribonucleotides; Polyorchis penicillatus; Protein Precursors - biosynthesis; Protein Precursors - chemistry; Protein Processing, Post-Translational; Protein Sorting Signals - metabolism; Proteins; Restriction Mapping; Sequence Homology, Amino Acid; C terminal-Sequence; Coelenterata; Molecular processing; Phenylalanine; Arginine; Cnidaria; Primary structure; Hydrozoa; Biosynthesis precursor; Invertebrata; Neuropeptide; Structural analysis
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2990431

Neuropeptides containing the C-terminal sequence Arg-Phe-NH2 (RFamide) occur throughout the Animal Kingdom and are abundant in evolutionarily 'old' nervous systems such as those of cnidarians. From the hydromedusa Polyorchis penicillatus we have previously isolated two neuropeptides, Pol-RFamide I (<Glu-Leu-Leu-Gly-Gly-Arg-Phe-NH2) and Pol-RFamide II (<Glu-Trp-Leu-Lys-Gly-Arg-Phe-NH2). Here we describe the cloning of a common precursor protein for these peptides from P. penicillatus. The precursor protein contains one copy of Pol-RFamide I, 11 copies of Pol-RFamide II and one putative neuropeptide sequence. The Pol-RFamide I sequence is flanked by pairs of basic residues (Arg-Lys). At the C-termini of all Pol-RFamide II sequences, single basic residues (Arg) occur. Paired and single basic residues are established sites for post-translational precursor cleavage. At the N-termini of the Pol-RFamide II sequences, however, basic residues are lacking and, instead, either single Asp (in eight cases) or single Asn residues (in three cases) occur. This means that processing must take place at Asp and/or Asn residues. This is firm evidence for the presence of one or more unconventional processing enzymes. The first type of processing enzyme could be an endoproteinase or aminopeptidase hydrolysing at the C-terminal side of Asp residues. Proteolytic cleavage at acidic amino acid residues has previously been inferred from other cnidarian neuropeptide precursors. The second type of processing enzyme could be an endoproteinase or aminopeptidase hydrolysing at the C-terminal side of Asn residues.