title: [Impacting of polymorphism of beta-amyrin synthase from Glycyrrhiza uralensis on its catalytic efficiency].
abstract: OBJECTIVE
  To analyze heterologous expression in Saccharomyces cerevisiae of two genotypes: beta-AS (A-T) genotype which is related to high content of glycyrrhizic acid and beta-AS(G-C) genotype which is related to low content of glycyrrhizic acid, and compare two different genotypes on the impact of beta-amyrin production in order to provide a foundation for licorice molecular breeding.
  
  
  METHODS
  The 2 289 bp fragment in plasmid pMD-19T encoding beta-amyrin synthase was subcloned into the yeast-Escherichia coli shuttle vector pY26, thus an expression recombinant plasmid PY-beta-AS containing target gene was constructed. The PY-beta-AS was introduced into defective mutant INVSc1 of S. cerevisiae by LiAc method, after induced by IPTG, the content of beta-amyrin was determined by GC-MS.
  
  
  RESULTS
  GC-MS analysis demonstrates that the an occurring peak corresponding to beta-amyrin standards was detected with the same retention time, which is absent in the cell transform with empty vector. Results showed the peak was beta-amyrin and the percentage of beta-amyrin in two genotypes: beta-AS (A-T) genotype and beta-AS (G-C) genotype were 19.08% and 1.40%, respectively. Thus the beta-amyrin synthase exhibited the activity of catalyzing 2, 3-oxidosqualene to beta-amyrin.
  
  
  CONCLUSIONS
  The catalytic efficiency of beta-AS(A-T) genotype is higher than that of beta-AS(G-C) genotype, which can lay the foundation for licorice molecular breeding.
authors.affiliation: School of Chinese Pharmacy, Beijing University of Chinese Medicine, Beijing 100102, China. dcrenen@163.com
authors.forename: Zhanyun
authors.initials: Z
authors.lastname: Shen
authors.forename: Chunsheng
authors.initials: C
authors.lastname: Liu
authors.forename: Jianmei
authors.initials: J
authors.lastname: Huang
authors.forename: Hongying
authors.initials: H
authors.lastname: Lin
authors.forename: Shuang
authors.initials: S
authors.lastname: Su
mesh_terms: D002384:Catalysis; D003001:Cloning, Molecular; D005838:Genotype; D029882:Glycyrrhiza uralensis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D019751:Intramolecular Transferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011110:Polymorphism, Genetic; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; D019751:Intramolecular Transferases; C039924:2,3-oxidosqualene-beta-amyrin-cyclase