3HZD: Crystal Structure Of Bothropstoxin-I (Bthtx-I), A Pla2 Homologue From Bothrops Jararacussu Venom

Phospholipases A(2) (Asp49-PLA(2)s) are enzymes responsible for cellular membrane disruption through Ca(2+)-dependent hydrolysis of phospholipids. A class of these proteins (Lys49-PLA(2)s) does not show catalytic activity but can exert a pronounced local myotoxic effect that is not neutralized by serum therapy. In this work, we present five structures of Lys49-PLA(2)s from snakes of the Bothrops genus in apo form, complexed with PEG molecules and chemically modified by p-bromofenacil bromide (BPB), a classic inhibitor of PLA(2). We present herein an extensive structural analysis including: (i) the function of hydrophobic long-chain molecules as Lys49-PLA(2)s inhibitors, (ii) the role of Lys122, previously indicated as being responsible for Lys49-PLA(2)s catalytic inactivity and, (iii) a structural comparison of the Ca(2+)-binding loop region between Lys49 and Asp49-PLA(2)s. The Lys122 analysis of 30 different monomers for apo and complexed Lys49-PLA(2)s structures shows that this residue is very flexible and may bind to different carboxyl groups giving stability to the crystal structures. The structural comparisons of the Ca(2+)-binding loop region between Lys49 and Asp49-PLA(2)s reveal the importance of the Tyr28 residue conservation in Asp49-PLA(2)s to the integrity of this loop. The Tyr28 residue stabilizes this region by an interaction with Gly35 residue. In Lys49-PLA(2)s and low-catalytic Asp49-PLA(2)s this interaction does not occur, preventing the binding of Ca(2+).
PDB ID: 3HZDDownload
MMDB ID: 75207
PDB Deposition Date: 2009/6/23
Updated in MMDB: 2011/12
Experimental Method:
x-ray diffraction
Resolution: 1.91  Å
Source Organism:
Similar Structures:
Biological Unit for 3HZD: dimeric; determined by author and by software (PISA)
Molecular Components in 3HZD
Label Count Molecule
Proteins (2 molecules)
Phospholipase A2 Homolog Bothropstoxin-1
Molecule annotation
Chemical (1 molecule)
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Citing MMDB