1. An expression cassette for expression of a protein of interest, wherein the said expression
cassette comprises of:
a) polynucleotide encoding T7 leader polypeptide comprising the amino acid sequence of
SEQ ID NO: 1;
b) a polynucleotide encoding expression tag polypeptide comprising of an amino acid
sequence selected from the group comprising of SEQ ID NO: 2-10;
c) a polynucleotide encoding a cleavable peptide linker; and
d) a polynucleotide encoding the protein of interest,
wherein the said polynucleotide sequences of the expression cassette are operably linked to a
promoter.
2. The expression cassette of claim 1, wherein the said expression cassette further comprises of a polynucleotide encoding a polyhistidine tag.
3. The expression cassette of claim 1, wherein the cleavable linker comprises of a modified TEV
protease cleavage site having the amino acid sequence as set forth in SEQ ID NO: 11.
4. The expression cassette of claim 1, wherein the protein of interest comprises of therapeutic
peptides which are less than 100 amino acids.
5. The expression cassette of claim 1, wherein the protein of interest is selected from the group
comprising of Lira-peptide, Teriparatide, Exenatide, Lixisenatide, Teduglutide, and Semaglutide.
6. The expression cassette of claim 1, wherein the protein of interest is Lira-peptide.
7. The expression cassette of claim 1, wherein the expression level of the protein of interest
increases by at least 85%.
8. An expression cassette for expression of lira-peptide, wherein the said expression cassette
comprises of:
a) a polynucleotide encoding T7 leader polypeptide comprising the amino acid sequence
of SEQ ID NO: 1; b) a polynucleotide encoding expression tag polypeptide comprising of an amino acid
sequence selected from the group comprising of SEQ ID NO: 2-10;
c) a polynucleotide encoding a cleavable peptide linker; and
d) a polynucleotide encoding lira-peptide comprising the amino acid sequence as set forth
in SEQ ID NO: 12 or a functional variant thereof, wherein the said polynucleotide sequences of the expression cassette are operably linked to a
promoter.
9. The expression cassette of claim 8, wherein the cleavable linker comprises of a modified TEV
protease cleavage site having the amino acid sequence as set forth in SEQ ID NO: 11.
10. The expression cassette of any one of claims 1-8, wherein the said expression cassette
comprises of polynucleotide sequence as set forth in SEQ ID NOs: 36-44
11. An expression vector for expression of a protein of interest, wherein the said expression vector
comprises of at least one copy of expression cassette from any one of claims 1-10.12. The expression cassette of claim 1 or the expression vector of claim 11 for use in the expression
of a protein of interest.
13. A host cell for enhanced production of a protein of interest comprising of an expression vector,
wherein the said expression vector comprises of any one of expression cassettes from claims 1-10.
14. The host cell of claim 13, wherein the said host cell is selected from a group comprising of E.
coli, Corynebacterium glutamicum and Bacillus subtilis.
15. The host cell of claim 14, wherein the E. coli strain is selected from the group comprising of
BL21 (DE3), BL21 Al, HMS174 (DE3), DH5ct, W31 10, B834, origami, Rosetta, NovaBlue
(DE3), Lemo21 (DE3), T7, ER2566 and C43 (DE3).
16. A fusion polypeptide comprising of:
a) a T7 leader polypeptide comprising the amino acid sequence of SEQ ID NO:1;
b) an expression tag polypeptide having an amino acid sequence selected from the group
comprising of SEQ ID NOs: 2-10; and
c) a cleavable peptide linker;fused to the amino-terminal of a protein of interest to obtain the fusion polypeptide.
17. The fusion polypeptide of claim 16, wherein the said fusion polypeptide further comprises of
a polyhistidine tag.
18. The fusion polypeptide of claim 16, wherein the cleavable linker comprises of modified TEV
protease cleavage site having the amino acid sequence as set forth in SEQ ID NO: 11.
19. The fusion polypeptide of claim 16, wherein the protein of interest comprises of therapeutic
peptides which are less than 100 amino acids long.
20. The fusion polypeptide of claim 16 wherein the protein of interest is selected from the group
comprising of Lira-peptide, Teriparatide, Exenatide, Lixisenatide, Teduglutide, and Semaglutide.21. The fusion polypeptide of claim 16, wherein the protein of interest is lira-peptide as set forth
in amino acid sequence of SEQ ID NO: 12 or functional equivalents thereof.
22. The fusion polypeptide of claim 16, wherein the said fusion polypeptide comprises of an amino
acid sequence as set forth in SEQ ID NOs: 14-22.
23. A method of producing a protein of interest, wherein the said method comprises the steps of:
a) culturing the host cell of any one of claims 13-15, under favorable conditions, to obtain
the fusion polypeptide of any one of claims 16-22;
b) isolating the fusion polypeptide obtained from step a); and c) cleaving the fusion polypeptide obtained from step b) at the cleavable linker to obtain
the protein of interest.
24. The method of claim 23, wherein the protein of interest is selected from the group comprising
of Lira-peptide, Teriparatide, Exenatide, Lixisenatide, Teduglutide, and Semaglutide.
25. The method of claim 23, wherein the protein of interest is lira-peptide as set forth in amino
acid sequence of SEQ ID NO: 12 or functional equivalents thereof.