A cytotoxic peptide from a marine sponge exhibits ion channel activity through vectorial-insertion into the membrane.
A cytotoxic peptide, polytheonamide B (pTB), from marine sponge was examined for cytotoxic spectrum and specific activity to mammalian cells was demonstrated. pTB is composed of alternative D- and L-amino acid residues throughout the 48-mer peptide. This suggests the formation of a β-helix similar to gramicidin channels. Planar bilayer experiments revealed that pTB forms monovalent cation-selective channels, being compatible with the inner pore diameter of ∼4Å for a β-helical structure. pTB penetrated vectorially into the membrane, formed a channel by means of a single molecule, and remained in the membrane. These functional properties may account for specific cytotoxic activity.
Iwamoto
Masayuki
M
Department of Molecular Physiology and Biophysics, University of Fukui Faculty of Medical Sciences, Fukui, Japan.
Shimizu
Hirofumi
H
Muramatsu
Ikunobu
I
Oiki
Shigetoshi
S
D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D003603:Cytotoxins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D047232:Theonella / Q000737:chemistry*
D003603:Cytotoxins; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; C111717:polytheonamide B