title: Agatoxin-like peptides in the neuroendocrine system of the honey bee and other insects.
abstract: We investigated the peptide inventory of the corpora cardiaca (CC) of the honey bee, Apis mellifera, by direct tissue profiling using MALDI-TOF MS combined with proteomic approaches focusing on cysteine-containing peptides. An agatoxin-like peptide (ALP) was identified as a component of the glandular part of the CC and was associated with the presence of the adipokinetic hormone in mass spectra. Although abundant in the CC, ALP does not belong to the toxins observed in the venom gland of A. mellifera. Homologs of ALP are highly conserved in major groups of arthropods and in line with this we detected ALP in the CC of non-venomous insects such as cockroaches and silverfish. In the American cockroach, Periplaneta americana, ALP was also identified in the CNS and stomatogastric nervous system. This is the first report that establishes the presence of ALPs in the neuroendocrine tissues of insects and further studies are necessary to reveal common functions of these peptides, e.g. as antimicrobial agents, ion channel modulators or classical neuropeptides.
  
  
  CONCLUSIONS
  Among the messenger molecules of the nervous system, neuropeptides represent the structurally most diverse class and basically participate in the regulation of all physiological processes. The set of neuropeptides, their functions and spatial distribution are particularly well-studied in insects. Until now, however, several potential neuropeptide receptors remained orphan, which indicates the existence of so far unknown ligands. In our study, we used proteomic methods such as cysteine modification, enzymatic digestion and peptide derivatization, combined with direct tissue profiling by MALDI-TOF mass spectrometry, for the discovery of novel putative messenger molecules in the neuroendocrine system. The described presence of agatoxin-like peptides in the nervous system of the honey bee and other insects was overseen so far and is thus a remarkable addition to the very well studied neuropeptidome of insects. It is not yet clear, if these toxin-like peptides act as antimicrobial agents, ion channel modulators or classical neuropeptides.
authors.affiliation: Institute for Zoology, University of Cologne, Zuelpicher Str. 47b, 50674 Cologne, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Sturm
authors.affiliation: Institute for Zoology, University of Cologne, Zuelpicher Str. 47b, 50674 Cologne, Germany; National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research (TIFR), Bangalore, 560065, India.
authors.forename: Divya
authors.initials: D
authors.lastname: Ramesh
authors.affiliation: National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research (TIFR), Bangalore, 560065, India.
authors.forename: Axel
authors.initials: A
authors.lastname: Brockmann
authors.affiliation: Institute for Zoology, University of Cologne, Zuelpicher Str. 47b, 50674 Cologne, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Neupert
authors.affiliation: Institute for Zoology, University of Cologne, Zuelpicher Str. 47b, 50674 Cologne, Germany. Electronic address: rpredel@uni-koeln.de.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Predel
mesh_terms: D060848:Agatoxins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001516:Bees / Q000378:metabolism*; D017124:Conserved Sequence; D007313:Insecta / Q000378:metabolism*; D008969:Molecular Sequence Data; D009490:Neurosecretory Systems / Q000378:metabolism*; D010455:Peptides / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D013045:Species Specificity
chemical_list: D060848:Agatoxins; D010455:Peptides
keywords: Adipokinetic hormone; Agatoxin; Apis mellifera; Insect neuropeptide; Periplaneta americana; Thermobia domestica