Prodynorphin in invertebrates

Area of Science:

• Neuroscience
• Biochemistry
• Evolutionary Biology

Background:

• Prodynorphin is a key precursor for opioid peptides in vertebrates.
• Understanding prodynorphin evolution requires studying its presence in diverse species.
• Invertebrate models offer insights into conserved biological mechanisms.

Purpose of the Study:

• To perform the first complete biochemical characterization of a prodynorphin-like molecule in an invertebrate.
• To investigate the structural and sequence homology of leech prodynorphin with vertebrate counterparts.
• To identify biologically active opioid peptides within the invertebrate precursor.

Main Methods:

• Purification of the 14270 Da protein using gel permeation chromatography, anti-leucine-enkephalin-affinity column, and reverse-phase HPLC.
• Complete characterization via Edman degradation, enzymatic treatments, and MALDI-TOF mass spectrometry.
• Sequence identity analysis compared to rat, human, and pig prodynorphins.

Main Results:

• A 119 amino-acid prodynorphin-like protein was identified in the leech Theromyzon tessulatum.
• The leech protein shows significant sequence identity to mammalian prodynorphins (e.g., 28.8% with rat).
• Alpha-Neo-endorphin, dynorphin-A, and dynorphin B-like peptides were identified at the C-terminus, with high sequence identity to mammalian forms (100%, 50%, 76.6% respectively). Leucine-enkephalin levels are comparable to vertebrates.
• Leech prodynorphin possesses a shorter N-terminus compared to mammalian prodynorphins.

Conclusions:

• This study provides the first comprehensive biochemical characterization of an invertebrate prodynorphin.
• The presence of conserved opioid peptide motifs suggests an ancient evolutionary origin for the prodynorphin system.
• The identified leech prodynorphin represents a valuable model for studying opioid peptide evolution and function across species.