Interisland variegation of venom [Lys49]phospholipase A2 isozyme genes in Protobothrops genus snakes in the southwestern islands of Japan.

Protobothrops tokarensis ( Pt ), a Crotalinae snake, inhabits only Takarajima and Kodakarajima islands of the Tokara Islands located in the immediate north of Amami-Oshima island of Japan. Kodakarajima P . tokarensis venom gland cDNA library gave four types of phospholipase A 2 (PLA 2 ) cDNAs encoding neutral [Asp 49 ]PLA 2 , basic [Asp 49 ]PLA 2 , highly basic [Asp 49 ]PLA 2 , and [Lys 49 ]PLA 2 . As the amino acid sequences encoded by their open reading frames (ORFs) were identical to those of PLA2, PLA-B, PLA-N, and BPI (a [Lys 49 ]PLA 2 ), respectively, from Amami-Oshima P. flavoviridis ( Pf ) venom, they were named Pt PLA2, Pt PLA-B, Pt PLA-N, and Pt BPI. Chromatography of P . tokarensis venom gave three PLA 2 isozymes, Pt PLA2, Pt PLA-B, and Pt BPI. However, BPII and BPIII ([Lys 49 ]PLA 2 s) expressed in Amami-Oshima P . flavoviridis venom were not found in P . tokarensis venom. Genomic polymerase chain reaction (PCR) for P . tokarensis liver DNAs with the unique primers gave Pt BPI gene. Notably it was found that LINE (long interspersed nuclear element)-1 fragment is inserted into second intron of Pt BPI gene. The LINE-1 fragment may prevent duplication of Pt BPI gene and thus formation of plural [Lys 49 ]PLA 2 genes in P . tokarensis genome. The interisland variegation of venom [Lys 49 ]PLA 2 isozyme genes in Protobothrops genus snakes in the southwestern islands of Japan is discussed. [ABSTRACT FROM AUTHOR]