title: Role of Tyr306 in the C-terminal fragment of Clostridium perfringens enterotoxin for modulation of tight junction.
abstract: We previously reported that the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) is a novel type of absorption enhancer that interacts with claudin-4 and that Tyr306 of C-CPE plays a role in ability of C-CPE to modulate barrier of tight junctions. In the current study, to investigate effects of Tyr306 on the C-CPE activity, we prepared some C-CPE mutants substituted Tyr306 with Trp (Y306W), Phe (Y306F) and Lys (Y306K). We found that Y306W and Y306F mutants of C-CPE had claudin-4 binding affinities and effects on the barrier function of tight junctions, whereas both of these properties were greatly reduced with the Y306K mutant. Finally, the Y306K but not the Y306F and Y306W mutants had reduced abilities to enhance absorption in rat jejunum. These results indicate that aromatic and hydrophobic properties, not hydrogen bonding potential, of Tyr306 are involved in the interaction of C-CPE with claudin-4 and in the modulation of the tight junction barrier function by C-CPE.
authors.affiliation: Department of Pharmaceutics and Biopharmaceutics, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan.
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ebihara
authors.forename: Masuo
authors.initials: M
authors.lastname: Kondoh
authors.forename: Motoki
authors.initials: M
authors.lastname: Harada
authors.forename: Makiko
authors.initials: M
authors.lastname: Fujii
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mizuguchi
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Tsunoda
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Horiguchi
authors.forename: Kiyohito
authors.initials: K
authors.lastname: Yagi
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D062506:Claudin-4; D004768:Enterotoxins / Q000633:toxicity*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D007583:Jejunum / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013329:Structure-Activity Relationship; D019108:Tight Junctions / Q000187:drug effects*
chemical_list: C568157:CLDN4 protein, human; D062506:Claudin-4; D004768:Enterotoxins; D008565:Membrane Proteins; D010446:Peptide Fragments; C035598:enterotoxin, Clostridium