1. Two novel tachykinin-related neuropeptides in the echiuroid worm, Urechis unicinctus
T Ikeda, H Minakata, K Nomoto, I Kubota, Y Muneoka Biochem Biophys Res Commun. 1993 Apr 15;192(1):1-6. doi: 10.1006/bbrc.1993.1373.
Two novel neuropeptides, urechistachykinin I (H-Leu-Arg-Gln-Ser-Gln-Phe-Val-Gly-Ser-Arg-NH2) and urechistachykinin II (H-Ala-Ala-Gly-Met-Gly-Phe-Phe-Gly-Ala-Arg-NH2), were isolated from the ventral nerve cords of the echiuroid worm, Urechis unicinctus. These peptides showed a contractile action on the inner circular body-wall muscle of the animal. Their amino acid sequences were found to be significantly homologous with those of the vertebrate and insect tachykinins. The urechistachykinins potentiated spontaneous rhythmic contractions of the cockroach hindgut.
2. The functional role of the tachykinin consensus region of urechistachykinin peptide family for its antimicrobial activity
Woo Sang Sung, Juneyoung Lee, Jaeyong Cho, Dong Gun Lee Biol Pharm Bull. 2011;34(6):921-4. doi: 10.1248/bpb.34.921.
In our previous study, we reported that urechistachykinin I (U I) and II (U II) exerted antimicrobial effects. To find out how the tachykinin consensus sequence of the urechistachykinin peptide family affects its antimicrobial activity, analogues substituting the amino acid residues phenylalanine (Phe-6; Anal 1), glycine (Gly-8; Anal 2), and arginine (Arg-10; Anal 3) of U II to alanine (Ala) were designed. Subsequently, the antimicrobial activity was shown on the order of Anal 3>U II=Anal 2>Anal 1, and this activity pattern was correlated with membrane studies such as propidium iodide (PI) influx and fluorescein isothiocyanate dextran (FD) leakage assay. These results suggest that the antimicrobial activity is related to the hydrophobicity values of the peptides. In regards to the activity of U II, it is determined that the hydrophobic Phe-6 plays a more critical role than Gly-8 or Arg-10.
3. Identification of multiple urechistachykinin peptides, gene expression, pharmacological activity, and detection using mass spectrometric analyses
T Kawada, K Masuda, H Satake, H Minakata, Y Muneoka, K Nomoto Peptides. 2000 Dec;21(12):1777-83. doi: 10.1016/s0196-9781(00)00338-7.
Urechistachykinin I and II (Uru-TK I and II) are invertebrate tachykinin-related peptides (TRPs), which have been isolated from echiuroid worms. The cDNA sequence encoding the Uru-TK I and II revealed that the precursor also encoded five TRP-like peptides. Here, we report the characterization of these Uru-TK-like peptides named as Uru-TK III-VII. Northern and Southern blot analyses demonstrated that Uru-TK mRNA is localized in nerve tissue. In addition, the presence of the Uru-TK-like peptides as matured forms in the nerve tissue was detected by mass spectrometric analysis, and identified these peptides were shown to exhibit a contractile activity on cockroach hindgut that was as potent as that of Uru-TK II. Furthermore, synthetic Uru-TK-like peptide analogs which contained Met-NH2 instead of Arg-NH2 at their C-termini were shown to possess a potential to bind to a mammalian tachykinin receptor, indicating that Uru-TK-like peptides are likely to correspond to vertebrate tachykinins, except for the difference at the C-terminal residue. These findings show that Uru-TK-like peptides are essentially equivalent to Uru-TK I and II, leading to the proposal that Uru-TK-like peptides play an essential role as invertebrate tachykinin neuropeptides.
