Download Design of specific peptide Inhibitors of Phospholipase A2

Design of specific peptide Inhibitors of Phospholipase A2:
Crystal structure of a complex formed between Russell's
viper Phospholipase A2 and a designed Peptide
V. Chandra1, J. Jasti1, P. Kaur1, S. Dey1, A. Srinivasan1, Ch. Betzel2 and T. P. Singh1
1Department
2Institute
of Biophysics, All India Institute of Medical sciences, New Delhi-110029, India
of Medical Biochemistry and Molecularbiology, University Hospital Hamburg Eppendorf, c/o DESY, Build.
22a, Notkestr. 85, 22603 Hamburg
Phospholipase A2 (E.C. 3.1.1.4) is a key enzyme of the cascade mechanism involved in the production of
proinflammatory compounds known as eicosanoids [1]. Specific inhibitor design is therefore of highest
interest [2,3]. The binding of phospholipase A2 to membrane surfaces and hydrolysis of phospholipids are
thought to involve the formation of a hydrophobic channel into which a single substrate molecule diffuses
before cleavage. In order to regulate the production of proinflammatory compounds, a specific peptide
inhibitor of PLA2, Leu-Ala-Ile-Tyr-Ser has been designed. Phospholipase A2 from Daboia russelli
pulchella (DPLA2) and peptide Leu-Ala-Ile-Tyr-Ser (LAIYS) have been co-crystallized. Diffraction data
were collected at the beam line X13. The structure of the complex has been determined and refined to 2.0
Å resolution. The structure contains two crystallographically independent molecules of DPLA2 with one
molecule of peptide specifically bound to one of them, as shown in figure 1. The overall conformations of
two molecules are essentially similar except in three regions, namely, the calcium binding loop including
Trp31 (residues: 25-34), the b-wing consisting of two antiparallel b-strands (residues: 74-85) and the Cterminal region (residues: 119-133). Out of these, the most striking difference pertains to the orientation
of Trp31 in the two molecules. The conformation of Trp31 in molecule A was suitable and allowed the
binding of peptide LAIYS while that in molecule B prevented the entry of the ligand into the hydrophobic
channel. The structure of the complex clearly showed that the OH group of Tyr of the inhibitor formed
hydrogen bonds with both His48 Nd and Asp49 Od1 while OgH of Ser was involved in a hydrogen bond
with Trp31. Other peptide backbone atoms interact with protein through water molecules while Leu, Ala
and Ile form strong hydrophobic interactions with the residues of the hydrophobic channel.
Figure 1 showing the specific peptide bound to the active site region
References
[1] Silhammer, J.J., Pruzanski, W., Vadas. P., Plant, S., Miller, J.A., Kloss, J. and Johnson, L.K., J.
Biol. Chem. 264, 5335-5341 (1989)
[2] Chandra, V., Jasti, J., Kaur, P., Betzel, Ch., Srinivasan, A. and Singh, T. P. J. Mol. Biol. 320, 215222 (2002)
[3] Chandra V., Jasti J., Kaur P., Srinivasan, A., Betzel, Ch. and T. P. Singh, Biochemistry 41, 1091410919 (2002)