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

Abstract

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 (Cys8 to Cys16) was identified.

Dehiscent organs used for defensive behavior of kamikaze termites of the genus Ruptitermes (Termitidae, Apicotermitinae) are not glands

“…It is known that the adhesive secretions used by insects during defense are constituted by many compounds such as proteins, polysaccharides, polyphenols, lipids (including terpenes and resins), glycoproteins, proteoglycans, phenolic proteins, and phenolic polysaccharides (Ambsdorf et al, 1992;Onusseit, 2004). For example, the labial glands of soldiers of Mastotermes darwiniensis (Mastotermitidae) contain a mixture of proteins and quinones (Moore, 1968;Quennedey, 1984); the frontal glands of many species of Rhinotermitidae contain a mixture of lipids, mucopolysaccharides, proteins, and terpenes (Blum et al, 1982;Moore, 1968;Negulescu et al, 2015;Piskorski et al, 2007); the frontal gland of Nasutitermitinae (Termitidae) soldiers contains ketones, esters, alcohol, monoterpenes, diterpenes, sesquiterpenes, and monoterpene acetates, among others (Costa-Leonardo and De Salvo, 1987;Grassé, 1982;Moore, 1964;Šobotník et al, 2010a). The results of the protein analysis conducted in this study are still preliminary but indicate that the secretion of dehiscent organs of R. reconditus and R. xanthochiton is constituted mainly by proteins of high molecular weight (200 kDa).…”

“…Other studies have shown that the proteins present in adhesive secretions have molecular weights ranging from 500 kDa to 8 kDa, although most of the peptides are below 300 kDa (Gnatzy et al, 2004;Jin et al, 2006;Li et al, 2008). Although much work has been done to determine the chemical composition of the defensive glands, as such frontal gland secretion of termites, the protein components of the secretions is relatively overlooked (Negulescu et al, 2015). The crystal gland of N. taracua produces copper-rich enzyme BP76 with a molecular weight of 76 kDa that participate in the oxidation of hydroquinones from salivary glands to benzoquinones (Bourguignon et al, 2015b;Šobotník et al, 2012).…”

“…The crystal gland of N. taracua produces copper-rich enzyme BP76 with a molecular weight of 76 kDa that participate in the oxidation of hydroquinones from salivary glands to benzoquinones (Bourguignon et al, 2015b;Šobotník et al, 2012). A recent research (Negulescu et al, 2015) detailed the protein TFP4 which is the first protein cloned and characterized from the frontal defense gland secretion of termite soldiers of Coptotermes formosanus and only the fourth protein from the order Isoptera (Da Silva et al, 2003;Jeng et al, 2011Jeng et al, , 2012Khademi et al, 2002).…”

A critical review on serine protease: Key immune manipulator and pathology mediator

“…123 Termite-derived Kazal-type inhibitor blocked activity of chymotrypsin and elastase. 124 A spider venom-derived Kunitz-type inhibitor inactivated plasmin and elastase. 125 Also, Kunitz type inhibitors have been discovered in the saliva of ticks.…”

Termite soldiers contribute to social immunity by synthesizing potent oral secretions

“…Aside from these abundant semiochemical compounds, there are a number of proteins in soldier secretions that have never been fully identified (Moore ). Studies in other insects have shown that excreted proteins can play an important role in digestion (Sillam‐Dusses et al ., ; Kambara et al ., ), defence (Negulescu et al ., ; Lawson et al ., ), immunity (Negulescu et al ., ; Palmer et al ., ), and caste regulation (Drapeau et al ., ). Given the importance of externally secreted molecules to eusocial insect immunity (Otti et al ., ), the highly enriched exocrine secretions of termite soldiers could make them ideal reservoirs of externally applied immune molecules.…”