Structural insight into the activation mechanism of human pancreatic prophospholipase A2.
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Xu W, Yi L, Feng Y, Chen L, Liu J
Structural insight into the activation mechanism of human pancreatic prophospholipase A2.
J Biol Chem. 2009 Jun 12;284(24):16659-66. doi: 10.1074/jbc.M808029200. Epub 2009 Mar 18.
- PubMed ID
- 19297324 [ View in PubMed]
- Abstract
Pancreatic phospholipase A2 (phospholipase A2 group 1B, G1B) belongs to the superfamily of secreted phospholipase A2 (PLA2) enzymes. G1B has been proposed to be a potential target for diseases such as hypertension, obesity, and diabetes. Human pancreatic prophospholipase A2 (pro-hG1B) is activated by cleavage of the first seven-residue propeptide (phospholipase A2 propeptide, PROP). However, questions still remain on the mode of action for pro-hG1B. In this work, we expressed pro-hG1B in Pichia pastoris and determined the crystal structure at 1.55-A resolution. The x-ray structure demonstrates that pro-hG1B forms a trimer. In addition, PROP occupies the catalytic cavity and can be self-cleaved at 37 degrees C. A new membrane-bound surface and activation mechanism are proposed based on the trimeric model of pro-hG1B. We also propose a new autoproteolytic mechanism for pro-hG1B by the reaction triad Asp49-Arg0-Ser(-2) that is similar to the serine protease catalytic triad.