A plant defensive cystatin (soyacystatin) targets cathepsin L-like digestive cysteine proteinases (DvCALs) in the larval midgut of western corn rootworm (Diabrotica virgifera virgifera).
Feeding bioassay results established that the soybean cysteine proteinase inhibitor N (soyacystatin N, scN) substantially inhibits growth and development of western corn rootworm (WCR), by attenuating digestive proteolysis [Zhao, Y. et al. (1996) Plant Physiol. 111, 1299-1306]. Recombinant scN was more inhibitory than the potent and broad specificity cysteine proteinase inhibitor E-64. WCR digestive proteolytic activity was separated by mildly denaturing SDS-PAGE into two fractions and in-gel assays confirmed that the proteinase activities of each were largely scN-sensitive. Since binding affinity to the target proteinase [Koiwa, H. et al. (1998) Plant J. 14, 371-380] governs the effectiveness of scN as a proteinase inhibitor and an insecticide, five peptides (28-33 kDa) were isolated from WCR gut extracts by scN affinity chromatographic separation. Analysis of the N-terminal sequence of these peptides revealed similarity to a cathepsin L-like cysteine proteinase (DvCAL1, Diabrotica virgifera virgifera cathepsin L) encoded by a WCR cDNA. Our results indicate that cathepsin L orthologs are pivotal digestive proteinases of WCR larvae, and are targets of plant defensive cystatins (phytocystatins), like scN.
Koiwa
H
H
Center for Plant Environmental Stress Physiology, Purdue University, West Lafayette, IN 47907-1163, USA.
Shade
R E
RE
Zhu-Salzman
K
K
D'Urzo
M P
MP
Murdock
L L
LL
Bressan
R A
RA
Hasegawa
P M
PM
D000595:Amino Acid Sequence; D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000737:chemistry; D003058:Cockroaches / Q000187:drug effects* / Q000201:enzymology; D015891:Cystatins / Q000494:pharmacology*; D003546:Cysteine Endopeptidases / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D010450:Endopeptidases; D007814:Larva / Q000187:drug effects; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D056668:Cathepsin L