A Kazal-Type Serine Protease Inhibitor from the Defense Gland Secretion of the Subterranean Termite Coptotermes formosanus Shiraki

• Published in: PloS one Vol. 10; no. 5; p. e0125376
• Main Authors: Negulescu, Horia, Guo, Youzhong, Garner, Thomas P, Goodwin, Octavia Y, Henderson, Gregg, Laine, Roger A, Macnaughtan, Megan A
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 15.05.2015; Public Library of Science (PLoS)
• Subjects: Amino acids; Animals; Base Sequence; Biochemistry; Body mass; Chemical bonds; Chemistry; Chymotrypsin; Coptotermes formosanus; DNA, Complementary - genetics; Economic impact; Elastase; Enzymes; Gene expression; Glands; Impact analysis; Isoptera; Isoptera - chemistry; Logos; Magnetic resonance; Magnetic Resonance Spectroscopy; Molecular biology; Molecular Sequence Data; Nasutitermes; Neotermes; NMR; Nuclear magnetic resonance; Nuclear magnetic resonance spectroscopy; Protease; Protease inhibitors; Proteins; Rhinotermitidae; Secretion; Serine; Serine proteinase; Serine Proteinase Inhibitors - chemistry; Soldiers (insect caste); Spectroscopy; Structure-function relationships; Termites; Trypsin; Louisiana; United States
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0125376

Coptotermes formosanus is an imported, subterranean termite species with the largest economic impact in the United States. The frontal glands of the soldier caste termites comprising one third of the body mass, contain a secretion expelled through a foramen in defense. The small molecule composition of the frontal gland secretion is well-characterized, but the proteins remain to be identified. Herein is reported the structure and function of one of several proteins found in the termite defense gland secretion. TFP4 is a 6.9 kDa, non-classical group 1 Kazal-type serine protease inhibitor with activity towards chymotrypsin and elastase, but not trypsin. The 3-dimensional solution structure of TFP4 was solved with nuclear magnetic resonance spectroscopy, and represents the first structure from the taxonomic family, Rhinotermitidae. Based on the structure of TFP4, the protease inhibitor active loop (Cys(8) to Cys(16)) was identified.