Glycoproteomics of the Zabrotes subfasciatus larval midgut associated with the insecticidal mechanism of the Olneya tesota PF2 lectin (1006.1)

Abstract

Insect midguts, as well as other animals, are rich in glycoconjugates that have important biological functions required for growth and development. Dietary lectins can bind to gut glycoconjugates and induce various insecticidal effects such as blocking of receptors or transporters and inactivation or activation of enzymes. PF2 is a lectin isolated from the seeds of Olneya tesota (Palo Fierro), and reported to cause 100% mortality of Zabrotes subfasciatus larvae (Mexican bean weevil). We evaluated recognition of the PF2 lectin by α‐amylases from Z. subfasciatus larval midgut and the effect of PF2 on α‐amylase activity. Results demonstrated PF2 decreased total midgut amylase activity. In‐gel amylase activity assay showed three enzyme isoforms, but only one isoform was recognized by PF2. The identity of this Z. subfasciatus α‐amylase was confirmed by LC‐MS/MS. We also evaluated the binding of PF2 to midgut glycoproteins at different larval stages using techniques such as chromatography, 2D‐gel electrophoresis and lectin blotting. Lectin interaction revealed differences in glycoprotein patterns at different larval stages. Analysis by LC‐MS/MS and searches of insect databases revealed several glycoproteins that may serve as potential targets for PF2 recognition. Each of the identified proteins is physiologically significant to weevil larvae and may be associated with the insecticidal mechanism of PF2.Grant Funding Source: Supported by funds from the CONACYT, the Arizona Ag Experiment Station and CALS