MALDI MS-MS analysis of Arachis hypogaea seed proteinase inhibitor

ABSTRACT: Plant Protease Inhibitors (PIs) plays an important role in defense and combat against insect pests and pathogens. In the present study, Bowman-Birk Inhibitor (BBI) was purified(���������8 kDa) from mature seeds of an interspecific advanced hybrid peanut variety (4368-1) using trypsin affinity and size exclusion chromatographic techniques. The one and two-dimensional (2-D) gel electrophoresis revealed the existence of purified protein as several isoinhibitors in higher ordered oligomers. However, all the resolved isoforms exhibited inhibitory activity against bovine trypsin and chymotrypsin which is observed under one and 2-D in-gel activity staining. One of the high intensity isoinhibitor spot (pI 5.9) from 2-D gel was subjected to MALDI TOF-TOF analysis. The MS-MS ionization of PMF peak 3313.817 m/z revealed the amino acid sequence ���������APPYFECVCVDTFDHCPASCNSCVCTR��������� showed identity with BBIs of Arachis hypogaea along with significant similarity with other legume BBIs, hence the purified protein from peanut is named as PnBBI. Also, other biochemical and biophysical characteristics of PnBBI such as low molecular mass, presence of several isoinhibitors and their oligomerization, predominance of antiparallel ������-sheets and random coils in secondary structure, reactive sites against trypsin and chymotrypsin, broad spectrum of stability towards extreme pH and temperature similar to the typical characteristics of BBIs. Surface plasmon resonance competitive binding analysis revealed the bifuncitonal PnBBI is a trypsin specific inhibitor with 1:2 stoiciometry compared to chymotrypsin. A concentration dependent self-assocition tendency of PnBBI was further confirmed by red shift in far-UV CD spectra. Furthermore, the insecticidal potential of PnBBI against Helicoverpa armigera was assessed by in vitro assays and in vivo feeding experiments. A significant reduction in larval body weight was observed with concomitant attenuation in activity of midgut trypsin-like proteases of H. armigera (HaTPs) fed on PnBBI supplemented diet. The one and two-dimensional zymography studies revealed disappearence of several isoforms of HaTP upon feeding with PnBBI. qRT-PCR analysis further suggest the role of PnBBI in not only inhibiting the activity of midgut trypsin and chymotrypsin-like proteases but also in modulating their expression. Taken together, the results provide a biochemical and molecular basis for introgressed resistance in peanut interspecific advanced hybrid variety against H. armigera.

INSTRUMENT(S): autoflex

ORGANISM(S): Arachis Hypogaea (peanut)

TISSUE(S): Plant Cell, Cotyledon

SUBMITTER: Kollipara Padmasree  

LAB HEAD: Kollipara Padmasree

PROVIDER: PXD016933 | Pride | 2020-02-18

REPOSITORIES: Pride