Bacterial cells, optimized nucleotide sequences and methods for improved expression of recombinant
In some embodiments, the present invention provides isolated nucleotide sequences that encode Clostridium difficile toxin B, wherein the isolated nucleotide sequences have been optimized for improved expression of the toxin B in a bacterial cell. Other embodiments of the present invention pertain to methods of expressing recombinant Clostridium difficile toxin B in a bacterial cell from the isolated nucleotide sequences of the present invention. In other embodiments, the present invention pertains to bacterial cells that comprise the isolated nucleotide sequences of the present invention. In further embodiments, the invention pertains to isolated peptides of recombinant Clostridium difficile toxin B that were derived from the isolated nucleotide sequences of the present invention.
1. An isolated nucleotide sequence encoding Clostridium difficile toxin B,
wherein said isolated nucleotide sequence has been optimized for improved expression of said toxin B in a bacterial cell; and
wherein said isolated nucleotide sequence comprises at least one of SEQ ID NOS. 1, 5, 6 and 11.
2. The isolated nucleotide sequence of claim 1 , wherein said isolated nucleotide sequence is flanked by restriction enzyme sites.
3. The isolated nucleotide sequence of claim 1 , wherein said isolated nucleotide sequence is in an expression vector.
4. The isolated nucleotide sequence of claim 1 , wherein said bacterial cell is Escherichia coli.
5. An isolated nucleotide sequence, wherein said isolated nucleotide sequence is mutagenized to encode an inactive form of Clostridium difficile toxin B.
6. The isolated nucleotide sequence of claim 5 , wherein said isolated nucleotide sequence comprises at least one of SEQ ID NOS. 7, 8, 9 and 10.
7. An isolated nucleotide sequence encoding a Clostridium difficile protein,
wherein said isolated nucleotide sequence is optimized for improved expression of the protein in a bacterial cell and is selected from SEQ ID NOS 1, 3, 5, 6, 7, 8, 9, 10 and 11,
wherein said optimization comprises the identification of one or more codons that rarely appear in said bacterial cell, and the replacement of said one or more codons with one or more codons that more frequently appear in said bacterial cell.
8. The isolated nucleotide sequence of claim 7 , wherein said isolated nucleotide sequence encodes an antigenic portion of toxin B.
9. The isolated nucleotide sequence of claim 7 , wherein said isolated nucleotide sequence encodes full length toxin B.
10. The isolated nucleotide sequence of claim 7 , wherein said isolated nucleotide sequence is mutagenized to encode an inactive form of Clostridium difficile toxin B.
11. A method of expressing recombinant a Clostridium difficile protein in a bacterial cell, said method comprising:
optimizing a nucleotide sequence encoding a Clostridium difficile toxin B protein, wherein said optimization comprises changing one or more codons in said nucleotide sequence, and wherein said optimization leads to improved protein expression in said bacterial cell;
introducing said nucleotide sequence into said bacterial cell; and
inducing an expression of said protein from said nucleotide sequence in said bacterial cell.
12. The method of claim 11 , wherein said method further comprises purifying said expressed protein from said bacterial cell.
13. The method of claim 11 , wherein said method further comprises mutagenizing said nucleotide sequence to encode an inactive form of Clostridium difficile toxin B.
14. The method of claim 11 , wherein said optimization further comprises:
the identification of one or more codons in said nucleotide sequence that rarely appear in said bacterial cell; and
the replacement of said one or more codons with one or more codons that more frequently appear in said bacterial cell.
15. The method of claim 11 , wherein said optimized nucleotide sequence is inserted into an IPTG-inducible expression vector before said introduction into said bacterial cell.
16. The method of claim 15 , wherein said induction comprises exposure of said bacterial cell to IPTG.
17. The method of claim 11 , wherein said bacterial cell is Escherichia coli.
18. A bacterial cell comprising an isolated nucleotide sequence encoding a Clostridium difficile protein,
wherein said isolated nucleotide sequence has been optimized for improved expression of protein in said bacterial cell; and
wherein said isolated nucleotide sequence comprises at least one of SEQ ID NOS.1, 3, 5, 6, 7, 8, 9, 10 and 11.
19. The bacterial cell of claim 18 , wherein said bacterial cell is Escherichia coli.
20. The bacterial cell of claim 18 , wherein said isolated nucleotide sequence in said bacterial cell has been mutagenized to encode an inactive form of Clostridium difficile toxin B.
21. A bacterial cell comprising an isolated nucleotide sequence encoding a Clostridium difficile protein,
wherein said isolated nucleotide sequence has been optimized for improved expression of protein in said bacterial cell, and is selected from SEQ ID NOS 1, 3, 5, 6, 7, 8, 9, 10 and 11,
wherein said optimization comprises the identification of one or more codons that rarely appear in said bacterial cell, and the replacement of said one or more codons with one or more codons that more frequently appear in said bacterial cell.
22. The bacterial cell of claim 21 , wherein said isolated nucleotide sequence in said bacterial cell has been mutagenized to encode an inactive form of Clostridium difficile toxin B.
23. An isolated peptide derived from recombinant Clostridium difficile protein, wherein said isolated peptide sequence comprises at least one of SEQ ID NOS. 12, 13, 16 and 17.