Overexpression of GlPNP, a gene positively correlated with adenosine biosynthesis, increases the adenosine content of Ganoderma lucidum

Abstract:

[Background] Ganoderma lucidum is a precious Chinese medicinal herb with both medicinal and edible values. Adenosine, one of the active components, endows the herb with immunomodulatory, anti-inflammatory, and anti-tumor activities. [Objective] To regulate the expression of key genes involved in adenosine biosynthesis to increase the adenosine production of G. lucidum. [Methods] We studied the correlations of the expression of adenosine synthase genes (GlATIC,GlPNP, and GlADK) with the adenosine content. The key enzyme genes that were positively correlated with the adenosine content of G. lucidum were screened out. The key enzyme genes in G. lucidum were cloned and overexpressed to investigate the effect of key enzyme gene overexpression on adenosine accumulation. [Results] The expression of GlPNP was positively correlated with adenosine content. The key gene GlPNP was cloned and overexpressed in G. lucidum. The cDNA of GlPNP was 969 bp in length. GlPNP displayed a trimeric quaternary structure, with a predicted molecular weight of 34.6 kDa. The expression levels of GlPNP in the transformants were 2.9–3.9 folds higher than that of the wild type on day 4. The adenosine content in the transformants increased by 78% and 63%, respectively, compared with that in the strain transformed with the blank vector. [Conclusion] Overexpression of GlPNP is an effective strategy to increase the production of adenosine.

Key words:Ganoderma lucidum;adenosine;purine nucleoside phosphorylase;overexpression