Molecular docking of protease from Metarhizium anisopliae and their toxic effect against model insect Galleria mellonella

•Virulent isolates of Metarhizium anisopliae was isolated using a Galleria baiting technique.•The molecular weight of extracellular protease was identified as 35-40 kDa.•Mycotoxic activity was higher in Tk6 isolate at 120 h.•The molecular mass of active protein band range from 1000 to 3000 m/z in MALDI-TOF.•Protease enzyme from Tk6 isolate enhances the binding stability with the insect template stand.

Fungal virulence has been mostly associated with cuticle-degrading enzymes, which form the first formidable barrier to pathogens and pass through certain discrete stages before breaching the insect cuticle. The present study was conducted to extract and purify the extracellular protease enzyme from three isolates from Metarhizium anisopliae. The molecular weight of protease enzyme from each isolate was identified using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and found to be 35-40 kDa. The partially purified enzymes were tested to identify its toxic effects against the developmental stages of IVth instar larvae of Galleria mellonella and the mortality of larvae among the three isolates was observed. The Tk6 isolate showed an ascending effect after 48 h of exposure, with highest mortality at 120 h post inoculation. It also showed more virulence against the model insect compared to other strains. Tk6 isolate's active protein band was analyzed by MALDI-TOF and docking study was carried out to find the interaction between the fungal and insect proteins.

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