1EQ9

CRYSTAL STRUCTURE OF FIRE ANT CHYMOTRYPSIN COMPLEXED TO PMSF

Summary for 1EQ9

• Entry DOI: 10.2210/pdb1eq9/pdb
• Descriptor: CHYMOTRYPSIN, phenylmethanesulfonic acid (3 entities in total)
• Functional Keywords: chymotrypsin, fire ant, serine proteinase, hydrolase
• Biological source: Solenopsis invicta (red fire ant)
• Cellular location: Secreted, extracellular space: Q7SIG2
• Total number of polymer chains: 2
• Total formula weight: 48420.22

Authors

Botos, I.,Meyer, E.,Nguyen, M.H.,Swanson, S.M.,Meyer, E.F. (deposition date: 2000-04-03, release date: 2000-10-03, Last modification date: 2024-10-30)

Primary citation

Botos, I.,Meyer, E.,Nguyen, M.,Swanson, S.M.,Koomen, J.M.,Russell, D.H.,Meyer, E.F.
The structure of an insect chymotrypsin.
J.Mol.Biol., 298:895-901, 2000

PubMed Abstract: The South American imported fire ant (Solenopsis invicta), without natural enemies in the United States, widely infests the southern United States, causing more than a half billion dollars in health and agriculture-related damage annually in Texas alone. Fire ants are resistant to most insecticides, so control will require a more fundamental understanding of their biochemistry and metabolism leading to the design of selective, ecologically safe insecticides. The 4th instar larvae play a crucial role in the nutrition of the colony by secreting proteinases (especially chymotrypsin) which digest food products for the entire colony. The first structure of an ant proteolytic enzyme, fire ant chymotrypsin, was determined to atomic resolution (1.7 A). A structural comparison of the ant and mammalian structures confirms the "universality" of the serine proteinase motif and reveals a difference at residues 147-148, which are proteolytically removed in the bovine enzyme but are firmly intact in the ant chymotrypsin, suggesting a different activation mechanism for the latter. Likewise, the absence of the covalently attached propeptide domain (1-15) further suggests an uncharacteristic activation mechanism. The presence of Gly189 in the S1 site is an atypical feature of this chymotrypsin and is comparable only to human leukocyte elastase, hornet chymotrypsin and fiddler crab collagenase. Binding studies confirm the chymotrypsin nature of this novel enzyme.

PubMed: 10801356
DOI: 10.1006/jmbi.2000.3699

Experimental method

X-RAY DIFFRACTION (1.7 Å)