Characterization of GMPP from Dendrobium huoshanense yielding GDP-D-mannose

Dendrobium huoshanense has been used for centuries in China and its polysaccharides are the main active components in treating loss of body fluids resulting from fever and asthenic symptoms. However, the biosynthetic pathway of polysaccharides in D. huoshanense remains to be elucidated. In this study, we obtained a guanosine diphosphate (GDP)-mannose pyrophosphorylase (DhGMPP) from D. huoshanense and characterized its function to catalyze the conversion of alpha-D-mannosephosphate to GDP-D-mannose involved in the production of polysaccharides. DhGMPP, with the open reading frame of 1,245 bp, was isolated from RNA-Seq data of D. huoshanense. Phylogenetic analysis as well as sequence characterization suggested its involvement in the biosynthesis of GDP-D-mannose. In vitro enzyme assay demonstrated that GMPP encoded a pyrophosphorylase that converted alpha-D-mannose-phosphate and GTP into GDP-D-mannose. Identification of DhGMPP could provide more insights into the mechanism concerning polysaccharide biosynthesis in D. huoshanense and be utilized for enhancing polysaccharide accumulation through metabolic engineering.

Automated summary

In this study, a guanosine diphosphate (GDP)-mannose pyrophosphorylase (DhGMPP) involved in the biosynthesis of polysaccharides in Dendrobium huoshanense was identified and characterized. Understanding the function of DhGMPP could provide insights into enhancing polysaccharide accumulation through metabolic engineering in D. huoshanense.