Role of cellulose response transporter-like protein CRT2 in cellulase induction in Trichoderma reesei

Abstract

Background Induction of cellulase in cellulolytic fungi Trichoderma reesei is strongly activated by cellulosic carbon sources. The transport of cellulosic inducer and the perception of inducing signal is generally considered as the critical process for cellulase induction, that the inducing signal would be perceived by a sugar transporter/transceptor in T. reesei. Several sugar transporters are coexpressed during the induction stage, but which function they serve and how they work collaboratively are still difficult to elucidate. Results In this study, we found that the constitutive expression of the cellulose response transporter-like protein CRT2 (previously identified as putative lactose permease TRE77517) improves cellulase induction on a cellulose, cellobiose or lactose medium. Functional studies indicate that the membrane-bound CRT2 is not a transporter of cellobiose, lactose or glucose in a yeast system, and it also does not affect cellobiose and lactose utilization in T. reesei. Further study reveals that CRT2 has a slightly similar function to the cellobiose transporter CRT1 in cellulase induction. Overexpression of CRT2 led to upregulation of CRT1 and the key transcription factor XYR1. Moreover, overexpression of CRT2 could partially compensate for the function loss of CRT1 on cellulase induction. Conclusions Our study uncovers the novel function of CRT2 in cellulase induction collaborated with CRT1 and XYR1, possibly as a signal transductor. These results deepen the understanding of the influence of sugar transporters in cellulase production.

Proteome profiling of Enriched Membrane-associated Proteins Unraveled a Novel Sophorose and cello-oligosaccharide Transporter in Trichoderma reesei

“…Accumulation of glucose inside the cell causes the carbon catabolite repression and cellulase production is limited. Interestingly, a T. reesei cellobiose transporter previously reported by our group, Tr69957 [35], the cellobiose transporter Tr_StrC (Trire2_67752)[36] and the transporter-like protein CTR2 that is reported to potentially acts as a signal transductor in cellulase induction [37] were not identi ed in this work, which could be explained by low abundance or by regulatory events at the post-transcriptional level.…”

Proteome profiling of enriched membrane-associated proteins unraveled a novel sophorose and cello-oligosaccharide transporter in Trichoderma reesei

“…Accumulation of glucose inside the cell causes the carbon catabolite repression and cellulase production is limited. Interestingly, a T. reesei cellobiose transporter previously reported by our group, Tr69957 [ 12 ], the cellobiose transporter Tr_StrC (Trire2_67752) [ 34 ] and the transporter-like protein CRT2 that is reported to potentially acts as a signal transductor in cellulase induction [ 35 ] were not identified in this work, which could be explained by low abundance or by regulatory events at the post-transcriptional level.…”