Single mutation at P1 of a chymotrypsin inhibitor changes it to a trypsin inhibitor: X-ray structural (2.15 Å) and biochemical basis

Khamrui, Susmita; Dasgupta, J.; Dattagupta, J.K.; Sen, U.

doi:10.1016/j.bbapap.2005.06.012

Cited by 24 publications

(25 citation statements)

References 26 publications

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“…2A), which determine (in)sensitivity to PIs. Experiments on synthetic polypeptide enzymes or 'pepzymes' [29] have provided initial clues on the alteration of the activity and/or specificity resulting from modifying key amino acids [30][31][32][33][34][35][36][37]. It does appear that we cannot yet predict functional properties based on structural features.…”

Section: Molecular Diversity Versus Functional Diversitymentioning

confidence: 99%

Structural and functional diversities in lepidopteran serine proteases

Srinivasan

Giri

Gupta

2006

Cellular and Molecular Biology Letters

211

164

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Primary protein-digestion in Lepidopteran larvae relies on serine proteases like trypsin and chymotrypsin. Efforts toward the classification and characterization of digestive proteases have unraveled a considerable diversity in the specificity and mechanistic classes of gut proteases. Though the evolutionary significance of mutations that lead to structural diversity in serine proteases has been well characterized, detailing the resultant functional diversity has continually posed a challenge to researchers. Functional diversity can be correlated to the adaptation of insects to various host-plants as well as to exposure of insects to naturally occurring antagonistic biomolecules such as plant-derived protease inhibitors (PIs) and lectins. Current research is focused on deciphering the changes in protease specificities and activities arising from altered amino acids at the active site, specificity-determining pockets and other regions, which influence activity. Some insight has been gained through in silico modeling and simulation experiments, aided by the limited availability of characterized proteases. We examine the structurally and functionally diverse Lepidopteran serine proteases, and assess their influence on larval digestive processes and on overall insect physiology.

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Section: Molecular Diversity Versus Functional Diversitymentioning

confidence: 99%

Structural and functional diversities in lepidopteran serine proteases

Srinivasan

Giri

Gupta

2006

Cellular and Molecular Biology Letters

211

164

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“…JIP21 contains the residues Leu-Ser, previously proposed as the binding site to chymotrypsin of the WCI, unlike the STI, with Arg-Ile as active residues for trypsin (Song and Suh, 1998). In fact, it has been described that a single mutation (Leu / Arg) in the reactive site converted WCI into a strong inhibitor of trypsin (Khamrui et al, 2005). Interestingly, the inhibitory site for chymotrypsin in the BBI also contains the residues Leu-Ser (Werner and Wemmer, 1991).…”

Section: Biochemical Characterization Of the Purified Proteinmentioning

confidence: 99%

A Novel Function for the Cathepsin D Inhibitor in Tomato

2006

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Proteinaceous aspartic proteinase inhibitors are rare in nature and are described in only a few plant species. One of them corresponds to a family of cathepsin D inhibitors (CDIs) described in potato (Solanum tuberosum), involving up to 15 isoforms with a high sequence similarity. In this work, we describe a tomato (Solanum lycopersicum) wound-inducible protein called jasmonic-induced protein 21 (JIP21). Sequence analysis of its cDNA predicted a putative function as a CDI. The JIP21 gene, whose protein has been demonstrated to be glycosylated, is constitutively expressed in flowers, stem, and fruit, and is inducible to high levels by wounding and methyl jasmonate in leaves of tomato plants. The genomic sequence of JIP21 shows that the gene is intronless and reveals the presence of both a methyl jasmonate box (TGACT) and a G-box (CACGT) in the promoter. In contrast to the presumed role of JIP21 based on sequence analysis, a detailed biochemical characterization of the purified protein uncovers a different function as a strong chymotrypsin inhibitor, which questions the previously predicted inhibitory activity against aspartic proteinases. Moreover, Egyptian cotton worm (Spodoptera littoralis) larvae fed on transgenic tomato plants overexpressing JIP21 present an increase in mortality and a delay in growth when compared with larvae fed on wild-type plants. These larvae belong to the Lepidoptera family whose main digestive enzymes have been described as being Ser proteases. All these results support the notion that tomato JIP21 should be considered as a chymotrypsin inhibitor belonging to the Ser proteinase inhibitors rather than a CDI. Therefore, we propose to name this protein tomato chymotrypsin inhibitor 21 (TCI21).

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“…4B), while WCI3 analyzed in earlier studies did not inhibit trypsin (Ghosh and Singh, 1997;Shibata et al, 1986;Kortt, 1980;Khamrui et al, 2005). Substitution of His (137) in WCI3 to Arg (137) in WCI2 and WCI5 ( Fig.…”

Section: Analysis Of Recombinant Inhibitor Proteinsmentioning

confidence: 75%