Hybrid sugar transporters with altered sugar transport activity and uses thereof

1. A hybrid sugar transporter having an altered sugar transporter activity and comprising an amino acid sequence having the following structure:

wherein NT is a N-terminal domain, TMD1 is a first transmembrane domain (TMD), J1 is a first junction domain, the dotted line represents further TMDx and Jx pairs wherein x is an integer and is less than n, TMDn is the nth TMD, CT is a C-terminal domain, n is 7 to 9, wherein at least one TMD is from a first sugar transporter and a second TMD is from a second sugar transporter, wherein the first sugar transporter and the second sugar transporter are heterologous to each other; wherein (a) the altered sugar transporter activity is the increased or enhanced activity for transporting a pentose; (b) NT is about 3 to 20 amino acid residues in length, each TMD is about 19 or 22 amino acid residues in length, each J is about 3 to 25 amino acid residues in length, CT is about 10 to 70 amino acid residues in length; and (c) each TMD is a TMD of AmSWEET1, AmSWEET2, AmSWEET3, AmSWEET4, AmSWEET5, AmSWEET6, ArSWEET1, ArSWEET2, ArSWEET3, BbSWEET1, BbSWEET2, BdSWEET1, BdSWEET2, CaSWEET1, CaSWEET2, CaSWEET3, CcSWEET1, CcSWEET2, ChSWEET1, ChSWEET2, ChSWEET3, CISWEET1, CmSWEET1, CpSWEET1, CspSWEET1, CsSWEET1, DcSWEET1, EhSWEET1, EhSWEET2, EhSWEET3, EhSWEET4, GhSWEET1, GhSWEET2, GhSWEET3, GppSWEET1, GppSWEET2, GppSWEET3, GprSWEET1, GprSWEET2, GprSWEET3, HcSWEET1, HcSWEET2, HcSWEET3, HcSWEET4, HcSWEET5, HpSWEET1, HpSWEET2, JspSWEET1, KaSWEET1, NcSWEET1, NcSWEET1A, NcSWEET1B, NcSWEET1C, NcSWEET1D, NcSWEET2, NcSWEET3, NcSWEET4, NcSWEET5, OmSWEET1, OmSWEET2, PfSWEET1, PfSWEET2, PgSWEET1, PspSWEET1, PsSWEET1, PsSWEET2, RaSWEET1, RbSWEET1, RgSWEET1, RgSWEET2, or RgSWEET3.

2. The hybrid sugar transporter of claim 1 , wherein each TMD is a TMD of a sugar transporter of Neocallimastix californiae, Anaeromyces robustus , or Piromyces finnis.

3. A nucleic acid molecule comprising an open reading frame (ORF) encoding the hybrid sugar transporter of claim 1 .

4. A vector comprising the nucleic acid of claim 3 .

5. An isolated host cell comprising the vector of claim 4 .

6. A method for constructing the vector of claim 4 , the method comprising: introducing the ORF encoding the hybrid sugar transporter into a vector to produce the vector encoding the hybrid sugar transporter.

7. A method for producing the hybrid sugar transporter, the method comprising: (a) providing the vector of claim 4 , (b) introducing the vector into an isolated host cell, and (c) culturing or growing the host cell in a culture medium such that the host cell expresses the hybrid sugar transporter and the host cell has an altered capability for transporting sugar into the host cell.

8. The hybrid sugar transporter of claim 1 , wherein n=7.

9. The hybrid sugar transporter of claim 1 , wherein TMD1, TMD2, TMD3, or TMD4 are SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, or SEQ ID NO: 6, respectively.

10. The hybrid sugar transporter of claim 9 , wherein TMD1, TMD2, TMD3, or TMD4 are TMD1, TMD2, TMD3, or TMD4, respectively, of Neocallimastix californiae SWEET1.

11. The hybrid sugar transporter of claim 1 , wherein TMD5, TMD6, or TMD7 are TMD5, TMD6, or TMD7, respectively, of Piromyces finnis SWEET2.

12. The hybrid sugar transporter of claim 9 , wherein n=7; TMD1, TMD2, TMD3, and TMD4 are TMD1, TMD2, TMD3, and TMD4, respectively, of Neocallimastix californiae SWEET1; and TMD5, TMD6, and TMD7 are TMD5, TMD6, and TMD7, respectively, of Piromyces finnis SWEET2.

13. The hybrid sugar transporter of claim 1 , wherein the NT comprises SEQ ID NO:2.

14. The hybrid sugar transporter of claim 1 , wherein the CT comprises SEQ ID NO: 16 or SEQ ID NO: 17.

15. The hybrid sugar transporter of claim 1 , wherein at least one TMD is from NcSWEET1 and a second TMD is from a second sugar transporter heterologous to NcSWEET1.