Evidence of a Critical Role for Cellodextrin Transporte 2

• Published in: PloS one Vol. 9; no. 2; p. e89330
• Main Authors: Cai, Pengli, Gu, Ruimeng, Wang, Bang, Li, Jingen, Wan, Li, Tian, Chaoguang, Ma, Yanhe
• Format: Journal Article
• Language: English
• Published: Public Library of Science 20.02.2014
• Subjects: Cellulose
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0089330

CDT-1 and CDT-2 are two cellodextrin transporters discovered in the filamentous fungus Neurospora crassa. Previous studies focused on characterizing the role of these transporters in only a few conditions, including cellulose degradation, and the function of these two transporters is not yet completely understood. In this study, we show that deletion of cdt-2, but not cdt-1, results in growth defects not only on Avicel but also on xylan. cdt-2 can be highly induced by xylan, and this mutant has a xylodextrin consumption defect. Transcriptomic analysis of the cdt-2 deletion strain on Avicel and xylan showed that major cellulase and hemicellulase genes were significantly down-regulated in the cdt-2 deletion strain and artificial over expression of cdt-2 in N. crassa increased cellulase and hemicellulase production. Together, these data clearly show that CDT-2 plays a critical role in hemicellulose sensing and utilization. This is the first time a sugar transporter has been assigned a function in the hemicellulose degradation pathway. Furthermore, we found that the transcription factor XLR-1 is the major regulator of cdt-2, while cdt-1 is primarily regulated by CLR-1. These results deepen our understanding of the functions of both cellodextrin transporters, particularly for CDT-2. Our study also provides novel insight into the mechanisms for hemicellulose sensing and utilization in N. crassa, and may be applicable to other cellulolytic filamentous fungi.