A knockdown gene approach identifies an insect vector membrane protein with leucin-rich repeats as one of the receptors for the VmpA adhesin of flavescence dorée phytoplasma.

INTRODUCTION

The adhesion of flavescence dorée phytoplasma to the midgut epithelium cells of their insect vectors is partially mediated by the variable membrane protein A (VmpA), an adhesin which shows lectin properties. In order to identify the insect receptor for VmpA, we identified cell proteins interacting with recombinant VmpA-His.

METHODS

The proteins were identified by mass spectrometry analysis of VmpA- protein complexes formed upon interaction assays. To assess their impact in VmpA binding, we reduced the expression of the candidate genes on cells in culture by dsRNA-mediated RNAi. The effect of candidate gene knockdown on VmpA binding was measured by the capacity of cells to bind VmpA-coated fluorescent beads.

RESULTS AND DISCUSSION

There were 13 candidate proteins possessing potential N-glycosylation sites and predicted transmembrane domains selected. The decrease of expression of an unknown transmembrane protein with leucine-rich repeat domains (uk1_LRR) was correlated with the decreased adhesion of VmpA beads to cells. The uk1_LRR was more expressed in digestive tubes than salivary glands of . The protein uk1_LRR could be implicated in the binding with VmpA in the early stages of insect infection following phytoplasmas ingestion.