Glucuronosyltransferase, gene encoding same and use thereof

Abstract

Provided are an enzyme involved in a glycyrrhizin biosynthetic system, a gene of the enzyme and use thereof in order to stably and continuously provide a large amount of glycyrrhizin. Glucuronosyltransferase with an activity of further transferring glucuronic acid to the hydroxy group at the 2-position of glucuronic acid in an oleanane-type triterpenoid monoglucuronide is identified to provide the transferase, a gene for the transferase and use thereof.

1 . A polypeptide having an activity to transfer glucuronic acid to the hydroxy group at the 2-position of glucuronic acid in an oleanane-type triterpenoid monoglucuronide. 
     
     
         2 . The polypeptide according to  claim 1 , wherein the oleanane-type triterpenoid monoglucuronide is selected from the group consisting of β-amyrin monoglucuronide, 11-oxo-β-amyrin monoglucuronide, 30-hydroxy-11-oxo-β-amyrin monoglucuronide, 30-hydroxy-β-amyrin monoglucuronide, 11-oxoglycyrrhetinic acid monoglucuronide and glycyrrhetinic acid monoglucuronide. 
     
     
         3 . The polypeptide according to  claim 1 , derived from a  Glycyrrhiza  plant or a  Medicago  plant. 
     
     
         4 . The polypeptide according to  claim 3 , wherein the  Glycyrrhiza  plant is  G. uralensis.    
     
     
         5 . The polypeptide according to  claim 1 , comprising an amino acid sequence represented by SEQ ID NO: 3. 
     
     
         6 . The polypeptide according to  claim 1 , comprising any of amino acid sequences of the following (a) to (c):
 (a) an amino acid sequence represented by SEQ ID NO: 4,   (b) an amino acid sequence derived from the amino acid sequence represented by SEQ ID NO: 4 by deletion, replacement or addition of one or several amino acids, and or   (c) an amino acid sequence having 80% or more identity with the amino acid sequence represented by SEQ ID NO: 4.   
     
     
         7 . A polynucleotide encoding the polypeptide according to  claim 1 . 
     
     
         8 . The polynucleotide according to  claim 7 , comprising any of nucleotide sequences of the following (d) to (g):
 (d) a nucleotide sequence represented by SEQ ID NO: 5,   (e) a nucleotide sequence derived from the nucleotide sequence represented by SEQ ID NO: 5 by deletion, replacement or addition of one or several nucleotides,   (f) a nucleotide sequence having 80% or more identity with the nucleotide sequence represented by SEQ ID NO: 5, or   (g) a nucleotide sequence capable of hybridizing with a complementary nucleotide sequence to the nucleotide sequence represented by SEQ ID NO: 5 under stringent conditions.   
     
     
         9 . A recombinant vector comprising the polynucleotide according to  claim 7 . 
     
     
         10 . The recombinant vector according to  claim 9 , which is an over-expression vector or a constitutive expression vector. 
     
     
         11 . A transformant comprising the recombinant vector according to  claim 9  or a progeny thereof. 
     
     
         12 . The transformant or a progeny thereof according to  claim 11 , which is a  Fabaceae  plant. 
     
     
         13 . A method for producing a polypeptide having an activity to transfer glucuronic acid to the hydroxy group at the 2-position of glucuronic acid in an oleanane-type triterpenoid monoglucuronide, comprising:
 culturing the transformant or progeny thereof according to  claim 11  and   extracting said polypeptide from the culture.   
     
     
         14 . A method for producing glycyrrhetinic acid monoglucuronide, comprising:
 suppressing an activity of the polypeptide according to  claim 1  in an individual or cell capable of biologically synthesizing glycyrrhizin from β-amyrin.   
     
     
         15 . The production method according to  claim 14 , wherein the suppression is to suppress an expression of a gene encoding said polypeptide or to suppress the polypeptide by a treatment with an activity inhibitor. 
     
     
         16 . A method for selecting a plant having the polynucleotide according to  claim 7  by detecting the presence or absence of the polynucleotide or expression thereof, comprising:
 subjecting a sample containing a nucleic acid prepared from a target plant to a nucleic acid amplification or nucleic acid hybridization using the polynucleotide or a fragment thereof and 
 detecting or quantifying the polynucleotide.