title: Characterization and antifungal activity of gazyumaru (Ficus microcarpa) latex chitinases: both the chitin-binding and the antifungal activities of class I chitinase are reinforced with increasing ionic strength.
abstract: Three chitinases, designated gazyumaru latex chitinase (GLx Chi)-A, -B, and -C, were purified from the latex of gazyumaru (Ficus microcarpa). GLx Chi-A,-B, and -C are an acidic class III (33 kDa, pI 4.0), a basic class I (32 kDa, pI 9.3), and a basic class II chitinase (27 kDa, pI > 10) respectively. GLx Chi-A did not exhibit any antifungal activity. At low ionic strength, GLx Chi-C exhibited strong antifungal activity, to a similar extent as GLx Chi-B. The antifungal activity of GLx Chi-C became weaker with increasing ionic strength, whereas that of GLx Chi-B became slightly stronger. GLx Chi-B and -C bound to the fungal cell-walls at low ionic strength, and then GLx Chi-C was dissociated from them by an escalation of ionic strength, but this was not the case for GLx Chi-B. The chitin-binding activity of GLx Chi-B was enhanced by increasing ionic strength. These results suggest that the chitin-binding domain of basic class I chitinase binds to the chitin in fungal cell walls by hydrophobic interaction and assists the antifungal action of the chitinase.
authors.affiliation: Department of Bioscience and Biotechnology, Faculty of Agriculture, Ryukyu University, Okinawa 903-0213, Japan. tokey@agr.u-ryukyu.ac.jp
authors.forename: Toki
authors.initials: T
authors.lastname: Taira
authors.forename: Atsuko
authors.initials: A
authors.lastname: Ohdomari
authors.forename: Naoya
authors.initials: N
authors.lastname: Nakama
authors.forename: Makiko
authors.initials: M
authors.lastname: Shimoji
authors.forename: Masanobu
authors.initials: M
authors.lastname: Ishihara
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002686:Chitin / Q000378:metabolism*; D002688:Chitinases / Q000737:chemistry / Q000145:classification* / Q000302:isolation & purification / Q000378:metabolism*; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D030681:Ficus / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007840:Latex / Q000378:metabolism*; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D016415:Sequence Alignment; D013696:Temperature
chemical_list: D000935:Antifungal Agents; D007840:Latex; D002686:Chitin; D002688:Chitinases