Characterisation of midgut digestive proteases from the maize stem borer Busseola fusca

George, D; Ferry, N; Back, E; Gatehouse, A

Abstract

BACKGROUND: Insect damage is a major constraint on maize production. Control of Busseola fusca (Fuller) in
sub-Saharan Africa is relatively ineffective; the major larval digestive enzymes were characterised with a view to
developing future control strategies.
RESULTS: Using BODIPY-FL Casein, maximal activity was at pH 9.5, with six protease forms visualised by
gelatin-PAGE. Synthetic substrates and diagnostic inhibitors demonstrated the presence of serine proteases.
Chymostatin was a potent inhibitor of general proteolysis (90%), providing strong evidence for the presence
of chymotrypsin; it also caused significant inhibition (>95%) with SA2PFpNA as substrate. The I50 values for
chymostatin with casein and SA2PFpNA were 0.0075 μM and 0.06 μM respectively. Z-Phe-Arg-pNA activity was
inhibited by chymostatin and TLCK (50 and 30% respectively), suggesting the presence of trypsin-like activity.
BApNA hydrolysis was also strongly inhibited by chymostatin and TLCK (92 and 75%), suggesting trypsin activity,
while SBBI, PMSF, pepstatin and E-64 had no significant effect. Interestingly, SBBI (I50 = 0.39 μM) and SBTI
both inhibited general proteolysis by approximately 70%, suggesting that SBBI’s dual inhibitory role makes this
inhibitor a potentially useful candidate for expression in maize for control of B. fusca.
CONCLUSION: These results provide a basis for the rational design of insect-resistant transgenic maize expressing
protease inhibitors.

Citation

George, D., Ferry, N., Back, E., & Gatehouse, A. (2008). Characterisation of midgut digestive proteases from the maize stem borer Busseola fusca. Pest Management Science, 64(11), 1151-1158. https://doi.org/10.1002/ps.1610

• Journal Article Type: Article
• Publication Date: Nov 1, 2008
• Deposit Date: Oct 6, 2011
• Journal: Pest Management Science
• Print ISSN: 1526-498X
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 64
• Issue: 11
• Pages: 1151-1158
• DOI: https://doi.org/10.1002/ps.1610
• Keywords: Digestive proteinases, protease inhibitors, stem borer, Busseola fusca, pest control strategies, maize
• Publisher URL: http://dx.doi.org/10.1002/ps.1610