ATP-binding cassette (ABC) transporters are a superfamily of proteins that transport nutrient substances and secondary metabolites through cell membranes. They also act as an uptake system for N,N'-diacetylchitobiose (GlcNAc)2 in Streptomyces coelicolor. (GlcNAc)2 is an important inducer of chitinase. However, whether the ABC transporter in Trichoderma spp. is also responsible for (GlcNAc)2 uptake and chitinase induction has not yet been confirmed. In this study, we applied RNA interference and overexpression technologies to alter the expression level of the ABC-B transporter in order to detect changes in its transportation ability and the expression level of inducible endo-chitinase ECH42-an important biocontrol enzyme in Trichoderma asperellum. The results revealed that, after interference with the expression of the ABC-B transporter, T. asperellum T4 was only able to grow normally when glucose was the only carbon source. Compared with the wild-type, the efficiency of (GlcNAc)2 by the overexpression strain evidently increased, along with the activity level of ECH42. In conclusion, one of the functions of the ABC-B transporter in T. asperellum is the uptake and transport of (GlcNAc)2 into cells, and chitobiose is a strong inducer of ECH42 in T. asperellum T4.
Keywords: ABC transporter; ECH42; Trichoderma asperellum; chitinase; chitobiose.