Effects of flippase DRS2 on expression and secretion of lignocellulases in Trichoderma reesei

Abstract:

[Objective] To study the effects of flippase DRS2 on the expression and secretion of lignocellulases in Trichoderma reesei.[Methods] The homologous gene drs2 in T. reesei was firstly identified through sequence alignment by BLAST and then deleted via homologous recombination strategy from T. reesei.The growth,protein secretion,and activities of cellulase and hemicellulase were compared between the drs2-deleted strain ∆drs2 and the control strain Cpyr4.Furthermore,the subcellular localization of DRS2 was predicted.[Results] Compared with Cpyr4,∆drs2 showed significantly decreased growth rate in the medium supplemented with glucose,lactose or microcrystalline cellulose (avicel).The total protein secretion and the activities of cellulase and hemicellulase of ∆drs2 were significantly higher than those of Cpyr4.The transcriptional levels of the key cellulase genes were similar between ∆drs2 and Cpyr4. Subcellular localization prediction revealed that DRS2 was located in spitzenkörper of the hypha tip.[Conclusion] The deletion of drs2 gene can significantly improve the production of lignocellulases in T. reesei cultured with cellulose as the sole carbon source. DRS2 may play a role in the secretion rather than the transcription of cellulases.

Key words:Trichoderma reesei;flippase;cellulase;protein secretion;gene deletion