title: Loss of introns along the evolutionary diversification pathway of snake venom disintegrins evidenced by sequence analysis of genomic DNA from Macrovipera lebetina transmediterranea and Echis ocellatus.
abstract: Analysis of cDNAs from Macrovipera lebetina transmediterranea (Mlt) and Echis ocellatus (Eo) venom gland libraries encoding disintegrins argued strongly for a common ancestry of the messengers of short disintegrins and those for precursors of dimeric disintegrin chains. We now report the sequence analysis of disintegrin-coding genes from these two vipers. Genomic DNAs for dimeric disintegrin subunits Ml_G1 and Ml_G2 (Mlt) and Eo_D3 (Eo) contain single 1-kb introns exhibiting the 5'-GTAAG (donor)/3'-AG (acceptor) consensus intron splicing signature. On the other hand, the short RTS-disintegrins Ml_G3 (Mlt) and Eo_RTS (Eo) and the short RGD-disintegrin ocellatusin (Eo) are transcribed from intronless genomic DNA sequences, indicating that the evolutionary pathway leading to the emergence of short disintegrins involved the removal of all intronic sequences. The insertion position of the intron within Ml_G1, Ml_G2, and Eo_D3 is conserved in the genes for vertebrate ADAM (A disintegrin and metalloproteinase) protein disintegrin-like domains and within the gene for the medium-size snake disintegrins halystatins 2 and 3. However, a comparative analysis of currently available disintegrin(-like) genes outlines the view that a minimization of both the gene organization and the protein structure underlies the evolution of the snake venom disintegrin family.
authors.affiliation: Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, B.P. 74, 1002, Tunis-Belvédère, Tunisia.
authors.forename: Amine
authors.initials: A
authors.lastname: Bazaa
authors.forename: Paula
authors.initials: P
authors.lastname: Juárez
authors.forename: Néziha
authors.initials: N
authors.lastname: Marrakchi
authors.forename: Zakaria
authors.initials: Z
authors.lastname: Bel Lasfer
authors.forename: Mohamed
authors.initials: M
authors.lastname: El Ayeb
authors.forename: Robert A
authors.initials: RA
authors.lastname: Harrison
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Calvete
authors.forename: Libia
authors.initials: L
authors.lastname: Sanz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D017931:DNA Primers; D018076:DNA, Complementary; D019483:Disintegrins / Q000235:genetics*; D014644:Genetic Variation; D007438:Introns; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014757:Viper Venoms / Q000737:chemistry / Q000235:genetics*; D017819:Viperidae / Q000145:classification* / Q000235:genetics*
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D019483:Disintegrins; D014757:Viper Venoms; D004247:DNA