Characterization, amino acid sequence and evolution of edema-inducing, basic phospholipase A(2) from Trimeresurus flavoviridis venom

Two phospholipases A(2) (PLA(2)s) were purified from the venom of Trimeresu rus flavoviridis (Crotalinae) inhabiting Tokunoshima island, Japan, and nam ed PLA-A and PLA-B in the order of elution on a cation-exchange column. Lip olytic activities of PLA-A and PLA-B toward mixed micelles and liposomes we re substantially lower than that of PLA2 (an [Asp(49)]PLA(2)) which had bee n isolated from the same venom. Both PLA-A and PLA-B consisted of 122 amino acids and contained aspartate at position 49 (the numbering according to t he aligned sequences of PLA(2)s in Fig. 8), thus belonging to an [Asp(49)]P LA(2) subgroup. PLA-A and PLA-B were identical in sequence with an exceptio n at position 79. PLA-B contained Asn-Gly at positions 79 and SO which are located in the beta -sheet region. On the other hand, PLA-A had beta -Asp-G ly and alpha -Asp-Gly in high and low proportion, respectively, at the corr esponding positions which were produced from Asn-Gly through the base-catal yzed formation and hydrolysis of the succinimide type intermediate. Thus, P LA-A is derived from PLA-B. PLA-B is similar in sequence to PL-X, which had been purified from the venom of T. flavoviridis inhabiting Amami-Oshima is land, Japan, and to PL-X', whose cDNA had been cloned from Tokunoshima T. f lavoviridis venom gland, rather than PLA2. PLA-B showed strong edema-induci ng activity, while PLA-A exhibited rather lower activity. The sequence arou nd position 79 which constitutes a beta -turn segment seems to be crucial f or edema-inducing activity. Phylogenetic tree of Tokunoshima T. flavoviridi s venom PLA(2) isozymes indicated that PLA-B and PL-X' diverged from PLA2 a fter branching of [Asp(49)]PLA(2) forms and [Lys(49)]PLA(2) forms. (C) 2001 Elsevier Science Ltd. All rights reserved.