The finding of a group IIE phospholipase A2 gene in a specified segment of Protobothrops flavoviridis genome and its possible evolutionary relationship to group IIA phospholipase A2 genes.

Takahito Chijiwa,Motonori Ohno,Kazuaki Yamaguchi,Yasuyuki Fukumaki,Hiroki Shibata,Shosaku Hattori,Naoko Oda-Ueda,Naoki Ikeda

doi:10.3390/toxins6123471

Takahito Chijiwa, Motonori Ohno + Show 6 more

Open Access

https://doi.org/10.3390/toxins6123471

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Journal: Toxins	Publication Date: Dec 18, 2014
Citations: 40	License type: CC BY 4.0

Affiliation: Sojo University, Kyushu University

Abstract

The genes encoding group IIE phospholipase A2, abbreviated as IIE PLA2, and its 5' and 3' flanking regions of Crotalinae snakes such as Protobothrops flavoviridis, P. tokarensis, P. elegans, and Ovophis okinavensis, were found and sequenced. The genes consisted of four exons and three introns and coded for 22 or 24 amino acid residues of the signal peptides and 134 amino acid residues of the mature proteins. These IIE PLA2s show high similarity to those from mammals and Colubridae snakes. The high expression level of IIE PLA2s in Crotalinae venom glands suggests that they should work as venomous proteins. The blast analysis indicated that the gene encoding OTUD3, which is ovarian tumor domain-containing protein 3, is located in the 3' downstream of IIE PLA2 gene. Moreover, a group IIA PLA2 gene was found in the 5' upstream of IIE PLA2 gene linked to the OTUD3 gene (OTUD3) in the P. flavoviridis genome. It became evident that the specified arrangement of IIA PLA2 gene, IIE PLA2 gene, and OTUD3 in this order is common in the genomes of humans to snakes. The present finding that the genes encoding various secretory PLA2s form a cluster in the genomes of humans to birds is closely related to the previous finding that six venom PLA2 isozyme genes are densely clustered in the so-called NIS-1 fragment of the P. flavoviridis genome. It is also suggested that venom IIA PLA2 genes may be evolutionarily derived from the IIE PLA2 gene.

Highlights

Protobothrops genus snakes (Crotalinae, Viperidae) are distributed in the southwestern islands ofJapan, P. flavoviridis and Ovophis okinavensis in Amami-Oshima, Tokunoshima, and the Okinawa islands, P. tokarensis in the Tokara islands, and P. elegans in the Sakishima islands
With regard to the primary structures and the modes of disulfide bond pairings [8], snake venom Phospholipase A2 (PLA2) are classified into group IA found in Elapidae (Elapinae and Hydrophiinae) venoms and group II found in Viperidae (Viperinae and Crotalinae) venoms [9]
Fry et al (2012) found that group IIE PLA2 was expressed in the venom glands of Colubridae snakes and proposed that it is a component of Colubridae snake venoms [17]

Summary

Introduction

Protobothrops genus snakes (Crotalinae, Viperidae) are distributed in the southwestern islands of. P. flavoviridis (Crotalinae) group IIA venom PLA2 genes form a multi-gene family of 16~32 copies per haploid [12] and are located at two loci on a microchromosome [13]. The nucleotide sequence of the 31,348 bp genome fragment of P. flavoviridis was completely deciphered It showed that six PLA2 isozyme genes are aligned in series and four of them are linked with the fragment of CR1 long interspersed nuclear element (LINE), named PcRTF (PLA2 gene-coupled reverse transcriptase fragment), at the 3' terminus [13]. It became evident that the linear arrangement of the IIA PLA2 gene, the IIE PLA2 gene, and OTUD3, in this order, is common in the genomes of humans to snakes. Possible conversion of the IIE PLA2 gene to the IIA PLA2 gene and its multiplication in Crotalinae snake genomes are discussed

Materials

Expression Analysis by Semi-Quantitative RT-PCR of Crotalinae IIE PLA2 mRNA

Phylogenetic Analysis of Secretory PLA2s

Results and Discussion

The Characteristic Primary Structures of Snake IIE PLA2 Proteins

Venom Gland-Specific Expression of IIE PLA2s in Crotalinae Snakes