Aminopeptidase N5 (APN5) as a Putative Functional Receptor of Cry1Ac Toxin in the Larvae of Athetis lepigone

Abstract

Athetis lepigone was a new lepidopteran pest and caused severe damage to maize crops in China. We have detected that Cry1Ac protoxin and toxin were highly active against the larvae of A. lepigone. However, there is no report about the mode of action of Bt Cry1Ac toxin against this pest until now. A 110 kDa APN5 protein from BBMV of A. lepigone was identified as the binding receptor of Cry1Ac toxin using Ligand blotting. The Cry1Ac receptor APN5 was cloned from A. lepigone larval midgut mRNA and named as AlAPN5 (GenBank accession no.: KU950745). AlAPN5 had a GATEN motif and been classified to Class 5 APNs. 79.2% reduction in mortality was observed when A. lepigone larvae were injected with siRNA of the AlAPN5 gene and treated with Cry1Ac toxin. These data demonstrate that AlAPN5 is a putative functional receptor and maybe the only receptor of Cry1Ac in A. lepigone.

Key Amino Acid Residues Influencing Binding Affinities of Pheromone-Binding Protein from Athetis lepigone to Two Sex Pheromones

“…Athetis lepigone Moschler (Lepidoptera: Noctuidae) is a polyphagous herbivore that is widely distributed in many European and Asian countries and has the ability to damage over 30 different types of cash crops. 21,22 From 2005 to 2011, the damage to summer maize by A. lepigone in northern China was documented to have increased gradually. More recently, A. lepigone has consolidated itself as an important maize pest, causing reductions in maize yield every year in China.…”

“…More recently, A. lepigone has consolidated itself as an important maize pest, causing reductions in maize yield every year in China. 22 Despite the important economic implications of this pest, an effective control strategy for this newly discovered pest has yet to be established. Pheromone-based pest management has always been considered as an efficient, green, and environmentally friendly control method.…”

The role of glycoconjugates as receptors for insecticidal proteins

“…Cry1Ac can bind to a class 4, 110 kDa APN present in H. virescens BBMV, that does not contain a C-terminal stalk and is not recognized by SBA (Banks et al 2001 ). Furthermore, a class 5 APN isolated from Athetis lepigone (AlAPN5) has recently been identified as a putative functional receptor mediating Cry1Ac toxicity (Wang et al 2017b ). This may indicate that the increased O-glycosylation sites seen in classes 1 and 3 are not responsible for Cry1Ac toxicity, although, to the best of our knowledge, it is unknown whether Cry1Ac binding to AlAPN5 is GalNAc-dependent.…”