The glucose high/low affinity dual transport system is a conservative strategy for microorganisms to deal with external environmental nutritional disturbances.
process of sensing and transporting glucose is closely related to cellulose degradation fungal expression regulation of fibrous enzymes.
as early as the 1970s, it was discovered that neurospora crassa, a cellulose-degrading fungus, enabled two transport systems with different affinity for glucose when dealing with high and low concentrations of glucose outside the cell: At high concentrations of glucose, the low affinity glucose transport system (System I) persists and plays a transshipment role, while at low concentrations of glucose or carbon hunger, the high affinity glucose transport system (System II) de-inhibits expression and transports limited nutrients outside the cell.
, however, it is not clear how the molecular components of the dual systems and their functions in their respective environments affect cellulase expression regulation, especially in terms of how they affect the regulation of cellulase expression.
The microbial functional genomics research team, led by Tian Chaoguang, a researcher at the Tianjin Institute of Industrial Biotechnology of the Chinese Academy of Sciences, identified the genetic components, physiological functions and synergetic regulation of the crude pulse spore glucose double transport system from the molecular level system, and discussed its significance for rough pulse spores to adapt to the environment of plant cellulose decay.
the working mode of glucose dual transport system in glucose transport, signal transducting and carbon metabolite containment regulation showed that GLT-1 had a high Km value (18.42 x 3.38 mM), while HGT -1/-2 has very low Km parameters (16.13 x 0.95 m and 98.97 x 22.02 m) respectively, which are the main components of System I and II (figure).
double-knocking of HGT-1/-2 significantly increased the yield of coarse pulse spore cellulosease by about twice.
Through a comparative analysis of a series of multi-mutants, it is found that HGT-1/-2 not only bears the transport of low concentrations of glucose, but also profoundly affects the process of carbon metabolism and signal transducting of cells;
-point mutation in HGT-1/-2, a conservative amino acid, HGT-1/-2 lost the function of glucose transport, but still has the effect of CCR regulation, indicating that it may be transducer-sensing dual-functional protein (transceptor).
this study provides a new understanding of fungal glucose transport, induction and cellulase expression regulation.
the study was funded by scientific and technological programs such as the National Natural Science Foundation of China, and the results were published in biotech for Biofuels, an international journal on bioenedy, with Wang Bang, a doctoral student at Tianjin Institute of Technology, as the first author of the paper.