Refined 2·0 Å X-ray Crystal Structure of the Snake Venom Zinc-endopeptidase Adamalysin II

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

“…GP1, GP2, and GP3 contained a second disulfide bond that linked the cysteine residues at positions 102 and 183, and for GP2, at amino acid positions 87 and 187. This second disulfide bond bridged the carboxyl terminus to the amino terminal end of the molecule in the same manner as shown by the crystal structures of rattlesnake metalloproteinases [34,35,[43][44][45]. Unexpectedly, the GP2 model had an additional third disulfide bond (149-171) that pulled the α-helix D towards the methionine-turn loop and which caused α-helix D to be partitioned into two smaller segments (Fig.…”

“…At the C-terminal domain, the four groups contained two short β-strands that harbor the Met turn. This structural region was arranged in the same order as reported for all RSVMPs [34,35,44,45].…”

“…3, contained two major structural domains, an upper N-terminal domain and a lower C-terminal domain. All the molecular models have four conserved a-helices, termed A, B, C, and D, and five N-terminal β-strands (I-V) that form the central hydrophobic β-pleated sheet core region, which is arranged in the same topological conformation as published for the crystal structures of adamalysin II of C. adamanteus [34,35,[43][44][45] and for atrolysin C (Ht-d) of C. atrox [34,35]. The C-terminal domain included a downward loop preceding the Zn +2 binding site but located after α-helix C. All four models had the same conformation for the methionine-turn (Met turn) with the methionine residue located approximately 2Å away from the zinc ion within the zinc binding pocket.…”

“…To address this hypothesis, we generated molecular models based on the translated amino acid sequences derived from the coding nucleotide regions of the mature proteinase domain for each of the four C. s. scutulatus metalloproteinase groups. The amino acid sequence of each isoform was folded in silico and compared to the known X-ray crystal structures of the hemorrhagic metalloproteinase atrolysin C (Ht-d) [35] and the non-hemorrhagic metalloproteinase adamalysin II [34].…”

The second zinc atom in the matrix metalloproteinase catalytic domain is absent in the full‐length enzymes: a possible role for the C‐terminal domain

“…The crystal structures of the catalytic domains of human neutrophil and fibroblast collagenases [2][3][4][5] and the NMR structure of the catalytic domain of human stromelysin-1 [6] have recently been reported. In addition, the structures of several other members of the metzincin family including the crayfish enzyme astacin [7,8], adamalysin II from snake venom [9] and the 50 kDa metalloproteinase from Serratia marcescens [10] have been solved. Despite limited sequence identity these enzymes share a common type of 3-D structure with an opensandwich topology in which two ~-helices are packed against a twisted t-sheet.…”