2BD1: A Possible Role Of The Second Calcium Ion In Interfacial Binding: Atomic And Medium Resolution Crystal Structures Of The Quadruple Mutant Of Phospholipase A2

Citation:
Abstract
The crystal structures of the monoclinic and trigonal forms of the quadruple mutant K53,56,120,121M of recombinant bovine pancreatic phospholipase A2 (PLA2) have been solved and refined at 1.9 and 1.1 A resolution, respectively. Interestingly, the monoclinic form reveals the presence of the second calcium ion. Furthermore, the surface-loop residues are ordered and the conformation of residues 62-66 is similar to that observed in other structures containing the second calcium ion. On the other hand, in the trigonal form the surface loop is disordered and the second calcium is absent. Docking studies suggest that the second calcium and residues Lys62 and Asp66 from the surface loop could be involved in the interaction with the polar head group of the membrane phospholipid. It is hypothesized that the two structures of the quadruple mutant, monoclinic and trigonal, represent the conformations of PLA2 at the lipid interface and in solution, respectively. A docked structure with a phospholipid molecule and with a transition-state analogue bound, one at the active site coordinating to the catalytic calcium and the other at the second calcium site, but both at the i-face, is presented.
PDB ID: 2BD1Download
MMDB ID: 39593
PDB Deposition Date: 2005/10/19
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.9  Å
Source Organism:
Similar Structures:
Biological Unit for 2BD1: monomeric; determined by author
Molecular Components in 2BD1
Label Count Molecule
Protein (1 molecule)
1
Phospholipase A2(Gene symbol: PLA2G1B)
Molecule annotation
Chemicals (4 molecules)
1
3
2
1
* Click molecule labels to explore molecular sequence information.

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