Sequence of a cDNA clone encoding the zinc metalloproteinase hemorrhagic toxin e from Crotalus atrox: evidence for signal, zymogen and disintegrin-like structures

Abstract

The sequence of two overlapping cDNA clones for the zinc metalloproteinase hemorrhagic toxin e (also known as atrolysin e, EC 3.4.24.44) from the venom gland of Crotalus atrox, the Western diamondback rattlesnake, is presented. The assembled cDNA sequence is 1975 nucleotides in length and encodes an open reading frame of 478 amino acids. The mature hemorrhagic toxin e protein as isolated from the crude venom has a molecular weight of approximately 24,000 and thus represents the processed product of this open reading frame. From the deduced amino acid sequence, it can be hypothesized that the enzyme is translated with a signal sequence of 18 amino acids, an amino-terminal propeptide of 169 amino acids, a central hemorrhagic proteinase domain of 202 amino acids, and a carboxy-terminal sequence of 89 amino acids. The propeptide has a short region similar to the region involved in the activation of matrix metalloproteinase zymogens. The proteinase domain is similar to other snake venom metalloproteinases, with over 57% identity to the low molecular weight proteinases HR2a and H2-proteinase from the Habu snake Trimeresurus flavoviridis. The carboxy-terminal region, which is not observed in the mature protein, strongly resembles the protein sequence immediately following the proteinase domain of HR1B (a high molecular weight hemorrhagic proteinase from the venom of T. flavoviridis) and the members of a different family of snake venom polypeptides known for their platelet aggregation inhibitory activity, the disintegrins. The cDNA sequence bears striking similarity to a previously reported sequence for a disintegrin cDNA. This report is evidence that this subfamily of venom metalloproteinases is synthesized in a proenzyme form which must be proteolytically activated.(ABSTRACT TRUNCATED AT 250 WORDS)

The metzincins — Topological and sequential relations between the astacins, adamalysins, serralysins, and matrixins (collagenases) define a super family of zinc‐peptidases

“…Similarly, as in the matrix metalloproteinases, a cysteine-switch mechanism has been proposed for these enzymes (Hite et al, 1992;Grams et al, 1994).…”

“…In their venom glands, snakes of the family Crotalidae (adders) produce extremely aggressive proteolytic enzymes, which can cause hemorrhage and tissue necrosis (see reviews by Bjarnason Takeya et al, 1990;Hite et al, 1992Hite et al, , 1994Kini & Evans, 1992). These toxins have been named adamalysins after adamalysin 11, an enzyme from the rattlesnake Crotalus adamanteus (Gomis-Ruth et al, 1993a.…”

“…The adamalysins are secreted as proenzymes. An N-terminal propeptide is cleaved off during activation (Hite et al, 1992). Some venom metalloproteinases contain additional regulatory mod-des, which are presumably responsible for interactions with the extracellular matrix.…”

Molecular models of the Mojave rattlesnake (Crotalus scutulatus scutulatus) venom metalloproteinases reveal a structural basis for differences in hemorrhagic activities

“…In the present study, an analysis of the depth or the distance between the S' 1 -pocket and the catalytic site cavity revealed no significant differences or correlation to hemorrhagic activities for the C. s. scutulatus metalloproteinase models. While the atrolysins have been characterized as hemorrhagic toxins that cleave similar substrates in vitro [55,56], the fact that their catalytic clefts superimpose well with each other but poorly to weakly hemorrhagic C. s. scutulatus metalloproteinases is consistent with this observation.…”

Inflammatory effects of snake venom metalloproteinases

“…Interestingly, there are metalloproteinases in snake venoms which are devoid of hemorrhagic activity (Willis & Tu 1988, Markland 1998. The structural basis of this observation is not clear, although some comparative studies have identified residues which may be required to exert this activity (Takeya et al 1990, Hite et al 1992, Ramos & Selistre-de-Araújo 2004.…”