Variant Sucrose Transporter Polypeptides That Enable Faster Sucrose Utilization In Bacteria

Abstract

Variant sucrose transporter polypeptides that enable faster sucrose utilization in bacteria are described. Additionally, variant or recombinant bacteria comprising these variant sucrose transporter polypeptides, and methods of utilizing the bacteria to produce products such as glycerol and glycerol-derived products are provided.

1 . (canceled) 
     
     
         2 . A bacterium comprising in its genome or on at least one recombinant construct:
 (a) a nucleotide sequence encoding a variant sucrose transporter polypeptide, said polypeptide having an amino acid sequence that has at least 95% identity to an amino acid sequence as set forth in SEQ ID NO:24 based on a Clustal W method of alignment and having at least one amino acid change selected from the group consisting of:
 (A) leucine to proline at position 61; 
 (B) leucine to tryptophan at position 61; 
 (C) leucine to histidine at position 61; 
 (D) leucine to phenylalanine at position 61; and 
 (E) leucine to tyrosine at position 61; 
   (b) a nucleotide sequence encoding a polypeptide having sucrose hydrolase activity;   
       wherein (a) and (b) are each operably linked to the same or a different promoter, further wherein said bacterium metabolizes sucrose at a greater rate than a bacterium containing a wild-type sucrose transporter polypeptide having an amino acid sequence as set forth in SEQ ID NO:24. 
     
     
         3 . The bacterium of  claim 2 , wherein the polypeptide having sucrose hydrolase activity is classified as EC 3.2.1.26 or EC 2.4.1.7. 
     
     
         4 . The bacterium of  claim 2  further comprising in its genome or on at least one recombinant construct, a nucleotide sequence encoding a polypeptide having fructokinase activity. 
     
     
         5 . The bacterium of  claim 4 , wherein the polypeptide having fructokinase activity is classified as EC 2.7.1.4, EC 2.7.1.3, or EC 2.7.1.1. 
     
     
         6 . The bacterium of  claim 2  wherein said bacterium is selected from the group consisting of the genera:  Escherichia, Klebsiella, Citrobacter , and  Aerobacter.    
     
     
         7 . The bacterium of  claim 6  wherein said bacterium is  Escherichia coli.    
     
     
         8 . The bacterium of  claim 2  wherein the bacterium is a recombinant bacterium that produces 1,3-propanediol, glycerol, and/or 3-hydroxypropionic acid. 
     
     
         9 . A process for making glycerol, 1,3-propanediol and/or 3-hydroxypropionic acid from sucrose comprising:
 a) culturing the recombinant bacterium of  claim 8  in the presence of sucrose; and   b) recovering the glycerol, 1,3-propanediol and/or 3-hydroxypropionic acid produced.