Isolation and molecular cloning of novel peptide toxins from the sea anemone Antheopsis maculata.
Three peptide toxins (Am I-III) with crab toxicity were isolated from the sea anemone Anthopleura maculata by gel filtration and reverse-phase HPLC. Am I was weakly lethal to crabs (LD50 830 microg/kg) and Am III was potently lethal (LD50 70 microg/kg), while Am II was only paralytic (ED50 420 microg/kg). The complete amino acid sequences of the three toxins were determined by cDNA cloning based on 3'-Race and 5'-Race. Although Am III (47 residues) is an analogue of the well-known type 1 sea anemone sodium channel toxins, both Am I (27 residues) and II (46 residues) are structurally novel peptide toxins. Am I is a new toxin having no sequence homologies with any toxins. Am II shares 28-39% identity with the recently characterized sea anemone toxins inhibiting specialized ion channels, BDS-I and II from Anemonia sulcata and APETx1 and 2 from Anthopleura elegantissima. The precursor proteins of the three toxins are commonly composed of a signal peptide, a propart with a pair of basic residues (Lys-Arg) at the end and the remaining portion. Very interestingly, the Am I precursor protein contains as many as six copies of Am I.
Honma
Tomohiro
T
Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo 108-8477, Japan.
Hasegawa
Yuichi
Y
Ishida
Masami
M
Nagai
Hiroshi
H
Nagashima
Yuji
Y
Shiomi
Kazuo
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003386:Brachyura / Q000187:drug effects; D003064:Cnidarian Venoms / Q000737:chemistry* / Q000494:pharmacology; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D012615:Sea Anemones; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D003064:Cnidarian Venoms; D010455:Peptides