Trichoderma virens Alt a 1 protein may target maize PR5/thaumatin-like protein to suppress plant defence: An in silico analysis

Abstract Trichoderma spp. are plant beneficial fungi that colonize roots, but unlike plant pathogens, impart defence. Recently, however, some small secreted cysteine-rich proteins have been identified in Trichoderma secretome, deletion of which improves induced defence. The mechanism of such “unusual” behaviour of a plant-beneficial fungus is not understood. In the present study, through in silico analysis, we attempted to explore if such proteins indeed suppress defence by interacting with plant proteins, much like pathogens, taking Alt a 1 protein of T. virens and maize PR5, a thaumatin-like defence protein as predicted interacting partners (with cue from some plant-pathogen interactions). Using computational analysis, we test the hypothesis that Trichoderma Alt a 1 inactivates maize PR5 to suppress plant defence in order to be able to colonize roots. The tertiary structures of both Alt a 1 and PR5 were modelled through homology as well as de novo modelling, followed by model validation through different quality check tools. Prior to protein-protein docking, MD (molecular dynamics) optimisation and refinement of computational models were carried-out. Docking results indicated that Alt a 1 exhibits strong binding affinity with PR5 suggesting that Alt a 1 and PR5 might interact much like in a plant-pathogen interactions resulting in suppression of plant defence to facilitate colonization.