Variant sucrose transporter polypeptides

Abstract

Variant sucrose transporter polypeptides that enable bacterial growth over a wide range of gene expression levels and sucrose concentrations are described. Additionally, 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 - 12 . (canceled) 
     
     
         13 . A variant sucrose transporter polypeptide having an amino acid sequence that has at least 95% identity to an amino acid sequence as set forth in SEQ ID NO:26 based on a Clustal W method of alignment and having an amino acid change from arginine to alanine or arginine to leucine at position 300, and comprising:
 at least one additional amino acid change selected from the group consisting of:
 (i) leucine to proline at position 61; 
 (ii) leucine to tryptophan at position 61; 
 (iii) leucine to histidine at position 61; 
 (iv) leucine to phenylalanine at position 61; and 
 (v) leucine to tyrosine at position 61. 
   
     
     
         14 . A variant sucrose transporter polypeptide having an amino acid sequence that has at least 95% identity based on a Clustal W method of alignment to an amino acid sequence selected from the group consisting of SEQ ID NOs: 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, and 98, and comprising an alanine at a position equivalent to position 300 when compared with a reference amino acid sequence of SEQ ID NO:26. 
     
     
         15 . The variant sucrose transporter polypeptide of claim  2 , wherein the variant sucrose transporter polypeptide further comprises: at least one of the following amino acids at an equivalent position when compared with the reference amino acid sequence of SEQ ID NO:26:
 (i) proline at a position equivalent to position 61;   (ii) tryptophan at a position equivalent to position 61;   (iii) histidine at a position equivalent to position 61;   (iv) phenylalanine at a position equivalent to position 61;   (v) tyrosine at a position equivalent to position 61.   
     
     
         16 . A variant sucrose transporter polypeptide having an amino acid sequence that has at least 95% identity based on a Clustal W method of alignment to an amino acid sequence selected from the group consisting of SEQ ID NOs: 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, and 98, and comprising: a leucine at a position equivalent to position 300 when compared with a reference amino acid sequence of SEQ ID NO:26; and at least one of the following amino acids at an equivalent position when compared with the reference amino acid sequence of SEQ ID NO:26:
 (i) proline at a position equivalent to position 61;   (ii) tryptophan at a position equivalent to position 61;   (iii) histidine at a position equivalent to position 61;   (iv) phenylalanine at a position equivalent to position 61;   (v) tyrosine at a position equivalent to position 61.