The recruitment of blood coagulation factor X into snake venom gland as a toxin

Summary

Trocarin D is a prothrombin activator from the Tropidechis carinatus venom. It is a functional and structural homologue to mammalian blood coagulation factor Xa.Trocarin D is hypothesised to have evolved from its factor X counterpart (TrFX) through gene duplication and recruitment.The genes of trocarin D and TrFX have significant sequence identities, except for insertions/deletions in their intron 1 and promoter regions. In trocarin D intron 1 region, there are three insertions and two deletions. In trocarin D promoter region, there is a novel 264 bp insertion which has potential cis-elements.This insertion is termed as Venom Recruitment/Switch Element (VERSE) and is hypothesised to account for switching the low-level constitutive expression of factor X in the liver to the high-level inducible expression of trocarin D in the venom gland. To understand the role of VERSE in the trocarin D expression,its cis-elements were characterised by luciferase assays in mammalian cell lines as well as snake venom gland cells. The ability of VERSE to drive luciferase expression is comparable to that of the trocarin D promoter. The predicted cis-elements are important in promoting expression as their mutagenesis resulted in lower luciferase expression.VERSE minimal core promoter and three novel cis-elements (two up-regulatory and one suppressor elements) were identified using deletion/site-directed mutagenesis studies. VERSE is primarily responsible for the increase of trocarin D expression. The insertions/deletions within trocarin D intron 1 need to be characterised for their role in tissue-specific and inducible expression of trocarin D.

Keywords

Factor X - promoter - prothrombin activator - recruitment - snake venom

• References

• 1 Tamiya T, Fujimi TJ. Molecular evolution of toxin genes in Elapidae snakes. Mol Divers 2006; 10: 529-543.
• 2 Reza MA, Minh LT, Swarup S. et al. Molecular evolution caught in action: gene duplication and evolution of molecular isoforms of prothrombin activators in Pseudonaja textilis (brown snake). J Thromb Haemost 2006; 04: 1346-1353.
• 3 Reza MA, Swarup S, Kini RM. Structure of two genes encoding parallel prothrombin activators in Tropidechis carinatus snake: gene duplication and recruitment of factor X gene to the venom gland. J Thromb Haemost 2007; 05: 117-126.
• 4 Fujimi TJ, Kariya Y, Tsuchiya T. et al. Nucleotide sequence of phospholipase A(2) gene expressed in snake pancreas reveals the molecular evolution of toxic phospholipase A(2) genes. Gene 2002; 292: 225-231.
• 5 Jeyaseelan K, Armugam A, Donghui M. et al. Structure and phylogeny of the venom group I phospholipase A(2) gene. Mol Biol Evol 2000; 17: 1010-1021.
• 6 Boshart M, Weber F, Jahn G. et al. A very strong enhancer is located upstream of an immediate early gene of human cytomegalovirus. Cell 1985; 41: 521-530.
• 7 Foecking MK, Hofstetter H. Powerful and versatile enhancer-promoter unit for mammalian expression vectors. Gene 1986; 45: 101-105.
• 8 Joseph JS, Chung MC, Jeyaseelan K. et al. Amino acid sequence of trocarin, a prothrombin activator from Tropidechis carinatus venom: its structural similarity to coagulation factor Xa. Blood 1999; 94: 621-631.
• 9 Fry BG, Wuster W. Assembling an arsenal: origin and evolution of the snake venom proteome inferred from phylogenetic analysis of toxin sequences. Mol Biol Evol 2004; 21: 870-883.
• 10 Fry BG, Scheib H, van der Weerd L. et al. Evolution of an arsenal: structural and functional diversification of the venom system in the advanced snakes (Caenophidia). Mol Cell Proteomics 2008; 07: 215-246.
• 11 Minh LT, Reza MA, Swarup S. et al. Gene duplication of coagulation factor V and origin of venom prothrombin activator in Pseudonaja textilis snake. Thromb Haemost 2005; 93: 420-429.
• 12 Rao VS, Kini RM. Pseutarin C, a prothrombin activator from Pseudonaja textilis venom: its structural and functional similarity to mammalian coagulation factor Xa-Va complex. Thromb Haemost 2002; 88: 611-619.
• 13 Rao VS, Swarup S, Kini RM. The nonenzymatic subunit of pseutarin C, a prothrombin activator from eastern brown snake (Pseudonaja textilis) venom, shows structural similarity to mammalian coagulation factor V. Blood 2003; 102: 1347-1354.
• 14 Rao VS, Swarup S, Kini RM. The catalytic subunit of pseutarin C, a group C prothrombin activator from the venom of Pseudonaja textilis, is structurally similar to mammalian blood coagulation factor Xa. Thromb Haemost 2004; 92: 509-521.
• 15 Rao VS, Joseph JS, Kini RM. Group D prothrombin activators from snake venom are structural homologues of mammalian blood coagulation factor Xa. Biochem J 2003; 369: 635-642.
• 16 Joseph JS, Valiyaveettil M, Gowda DC. et al. Occurrence of O-linked Xyl-GlcNAc and Xyl-Glc disaccharides in trocarin, a factor Xa homolog from snake venom. J Thromb Haemost 2003; 01: 545-550.
• 17 Masci PP, Whitaker AN, de Jersey J. Purification and characterization of a prothrombin activator from the venom of the Australian brown snake, Pseudonaja textilis textilis. Biochem Int 1988; 17: 825-835.
• 18 Reza MA, Swarup S, Kini RM. Gene structures of trocarin D and coagulation factor X, two functionally diverse prothrombin activators from Australian rough scaled snake. Pathophysiol Haemost Thromb 2005; 34: 205-208.
• 19 Hung HL, Pollak ES, Kudaravalli RD. et al. Regulation of human coagulation factor X gene expression by GATA-4 and the Sp family of transcription factors. Blood 2001; 97: 946-951.
• 20 Blissard GW, Kogan PH, Wei R. et al. A synthetic early promoter from a baculovirus: roles of the TATA box and conserved start site CAGT sequence in basal levels of transcription. Virology 1992; 190: 783-793.
• 21 Tafuri SR, Wolffe AP. Xenopus Y-box transcription factors: molecular cloning, functional analysis and developmental regulation. Proc Natl Acad Sci USA 1990; 87: 9028-9032.
• 22 Thomm M. Archaeal transcription factors and their role in transcription initiation. FEMS Microbiol Rev 1996; 18: 159-171.
• 23 Buratowski S, Hahn S, Guarente L. et al. Five intermediate complexes in transcription initiation by RNA polymerase II. Cell 1989; 56: 549-561.
• 24 Concino MF, Lee RF, Merryweather JP. et al. The adenovirus major late promoter TATA box and initiation site are both necessary for transcription in vitro. Nucleic Acids Res 1984; 12: 7423-7433.
• 25 Joseph JS, Thirumangalathu S, Tsang F. et al. Trocarin, a blood coagulation factor Xa homologue from snake venom, causes inflammation and mitogenesis. Toxicon 2003; 42: 769-776.
• 26 Reza A, Kini RM. Prothrombin Activators from Australian Snakes. Toxin Rev 2006; 25: 257-290.
• 27 Bode J, Kohwi Y, Dickinson L. et al. Biological significance of unwinding capability of nuclear matrix-associating DNAs. Science 1992; 255: 195-197.
• 28 Schubeler D, Mielke C, Maass K. et al. Scaffold/ matrix-attached regions act upon transcription in a context-dependent manner. Biochemistry 1996; 35: 11160-11169.
• 29 Huang MN, Hung HL, Stanfield-Oakley SA. et al. Characterization of the human blood coagulation factor X promoter. J Biol Chem 1992; 267: 15440-15446.
• 30 Wilberding JA, Castellino FJ. Characterization of the murine coagulation factor X promoter. Thromb Haemost 2000; 84: 1031-1038.