title: Purification and Partial Characterization of Trypsin-Specific Proteinase Inhibitors from Pigeonpea Wild Relative Cajanus platycarpus L. (Fabaceae) Active against Gut Proteases of Lepidopteran Pest Helicoverpa armigera.
abstract: Proteinase inhibitors (PIs) are natural defense proteins of plants found to be active against gut proteases of various insects. A pigeonpea wild relative Cajanus platycarpus was identified as a source of resistance against Helicoverpa armigera, a most devastating pest of several crops including pigeonpea. In the light of earlier studies, trypsin-specific PIs (CpPI 63) were purified from mature dry seeds of C. platycarpus (ICPW-63) and characterized their biochemical properties in contributing to H. armigera resistance. CpPI 63 possessed significant H. armigera gut trypsin-like proteinase inhibitor (HGPI) activity than trypsin inhibitor (TI) activity. Analysis of CpPI 63 using two-dimensional (2-D) electrophoresis and matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry revealed that it contained several isoinhibitors and small oligomers with masses ranging between 6 and 58 kDa. The gelatin activity staining studies suggest that these isoinhibitors and oligomers possessed strong inhibitory activity against H. armigera gut trypsin-like proteases (HGPs). The N-terminal sequence of the isoinhibitors (pI 6.6 and pI 5.6) of CpPI 63 exhibited 80% homology with several Kunitz trypsin inhibitors (KTIs) as well as miraculin-like proteins (MLPs). Further, modification of lysine residue(s) lead to 80% loss in both TI and HGPI activities of CpPI 63. In contrast, the TI and HGPI activities of CpPI 63 were stable over a wide range of temperature and pH conditions. The reported results provide a biochemical basis for pod borer resistance in C. platycarpus.
authors.affiliation: Department of Plant Sciences, School of Life Sciences, University of Hyderabad Hyderabad, India.
authors.forename: Marri
authors.initials: M
authors.lastname: Swathi
authors.affiliation: Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad Hyderabad, India.
authors.forename: Prashant K
authors.initials: PK
authors.lastname: Mishra
authors.affiliation: Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad Hyderabad, India.
authors.forename: Vadthya
authors.initials: V
authors.lastname: Lokya
authors.affiliation: Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad Hyderabad, India.
authors.forename: Vanka
authors.initials: V
authors.lastname: Swaroop
authors.affiliation: Legumes Cell biology, Grain Legumes Program, ICRISAT Hyderabad, India.
authors.forename: Nalini
authors.initials: N
authors.lastname: Mallikarjuna
authors.affiliation: Department of Animal Biology, School of Life Sciences, University of Hyderabad Hyderabad, India.
authors.forename: Aparna
authors.initials: A
authors.lastname: Dutta-Gupta
authors.affiliation: Department of Biotechnology and Bioinformatics, School of Life Sciences, University of Hyderabad Hyderabad, India.
authors.forename: Kollipara
authors.initials: K
authors.lastname: Padmasree
keywords: Kunitz trypsin inhibitor; gelatin activity staining; mass spectrometry; miraculin-like proteins; two-dimensional electrophoresis