[Antioxidation and multidrug resistance of structure-similar ATP-binding cassette transporter proteins in two fungal entomopathogens].

Objective: Structure-similar ATP-binding cassette (ABC) transporter proteins, BbT1 in Beauveria bassiana (Bb) and IfT1 in Isaria fumosorosea (If), were characterized.

Methods: Various phenotypes including cellular antioxidant response, multidrug resistance and virulence were compared between wild-type strain and the constructed mutants DeltaBbT1, DeltaBbT1/BbT1 and DBbT1/IfT1.

Results: Compared with the wild-type, DeltaBbT1/BbT1 and DeltaBbT1/ IfT1 strains showing no significant changes in examined phenotypes, DeltaBbT1 became 27% to 2.1-fold less tolerant to the oxidative stress of 20-40 mmol/L H2O2 and 2-8 mmol/L menadione, 28% to 4.7-fold less resistant to carbendazim, itraconazole, dimetachlone, cycloheximide, ethirimol and 4-nitroquinoline N-oxide, and about 20% less virulent to the second-instar larvae of Spodoptera litura.

Conclusion: The ABC transporter proteins BbT1 and IfT1 are similar not only in sequence structure but also in biological function, act as one of the determinants for the multidrug resistance of Bb and If, and also contribute to the fungal virulence due to involvement in cellular antioxidant response.