Methods and systems for engineering bacterial systems to shield toxicity during non-native protein expression and purification

1. A method to provide a toxic non-native protein in a cell, the method comprising

introducing into the cell at least one first polynucleotide encoding at least one microcompartment protein, the at least one polynucleotide operatively linked to one or more first regulatory elements leading to the expression of the at least one microcompartment protein in the cell, the at least one microcompartment protein capable of assembling with one or more same and/or different microcompartment proteins to form at least one empty microcompartment within the cell; and

introducing into the cell at least one second polynucleotide encoding for one or more toxic non-native proteins capable of reacting with a native membrane substrate with a reaction resulting in a cell damage, each of the one or more toxic non-native proteins operably linked to a leader peptide capable of directing expressed proteins to the at least one empty microcompartment, the at least one second polynucleotide operably linked to one or more second regulatory elements leading to the expression of the at least one toxic non-native protein operably linked to the leader peptide in the cell;

to obtain the toxic non-native protein within the at least one empty microcompartment within the cell.

2. The method of claim 1 , wherein the native membrane substrate is a substrate located in a plasma membrane, an outer membrane or a cell wall of the cell.

3. The method of claim 1 , wherein the native membrane substrate are selected from native membrane lipids, native membrane proteins and native peptidoglycans.

4. The method of claim 1 , wherein the one or more non-native toxic proteins comprise at least one non-native antimicrobial peptide.

5. The method of claim 4 , wherein the at least one non-native antimicrobial peptide is selected from a cationic antimicrobial peptide capable of reacting with native phospholipids in a plasma membrane of the cell, a cationic antimicrobial peptide capable of reacting with a native outer membrane, and a cationic antimicrobial peptide capable of reacting with a native outer membrane protein.

6. The method of claim 4 wherein the at least one non-native antimicrobial peptide is selected from cecropins, magainins, melittin, protegrins, and nisins.

7. The method of claim 1 , wherein the one or more non-native toxic proteins comprise one or more non-native proteases capable of reacting with a native membrane substrate.

8. The method of claim 1 , wherein the one or more non-native toxic proteins comprise one or more non-native proteases and one or more of non-native lysins.

9. The method of claim 1 , wherein the one or more non-native toxic proteins comprise chemotherapic non-native proteins.

10. The method of claim 1 , wherein introducing into the cell the at least one first polynucleotide is performed by introducing an expression vector comprising at least one polynucleotide of the at least one first polynucleotide and the one or more first regulatory elements in a configuration leading to transcription of the microcompartment protein carried on the expression vector.

11. The method of claim 1 , wherein introducing into the cell the at least one second polynucleotide encoding for the toxic non-native protein is performed by introducing an expression vector comprising the at least one polynucleotide of the at least one second polynucleotide and the one or more second regulatory elements in a configuration leading to transcription of the toxic non-native protein carried on the expression vector.

12. The method of claim 1 , wherein the at least one first polynucleotide comprises one or more polynucleotides encoding for two or more microcompartment proteins.

13. A system for shielding a bacterial cell from toxicity during intracellular production of a toxic non-native protein, the system comprising

at least one first polynucleotide encoding at least one microcompartment protein operatively linked to one or more first regulatory elements leading to the expression of the at least one microcompartment protein in the cell, the at least one microcompartment protein capable of assembling with one or more same and/or different microcompartment proteins to form at least one empty microcompartment within the cell; and

at least one second polynucleotide encoding for at least one toxic non-native protein capable of reacting with a native membrane substrate with a reaction resulting in a cell damage each of the one or more toxic non-native proteins operably linked to a leader peptide capable of directing expressed proteins to the at least one empty microcompartment, the at least one second polynucleotide operatively linked to one or more second regulatory elements leading to the expression of the at least one toxic non-native protein operably linked to the leader peptide.

14. The system of claim 13 , wherein the at least one first polynucleotide and the one or more first regulatory elements are comprised within an expression vector wherein the one or more first regulatory elements and the at least one first polynucleotide are located in a configuration leading to transcription of the at least one microcompartment protein carried on the expression vector.

15. The system of claim 13 , wherein the at least one second polynucleotide and one or more second regulatory elements are comprised within an expression vector wherein the at least one second polynucleotide and the one or more second regulatory elements are located in a configuration leading to efficient transcription of the at least one toxic non-native protein carried on the expression vector.

16. The system of claim 13 , wherein the one or more first regulatory elements comprise an enhancer and/or an over-expression promoter.

17. The system of claim 13 , wherein the one or more second regulatory elements comprise a low-level constitutive promoter.

18. The system of claim 13 , wherein the one or more first regulatory elements and/or the one or more second regulatory elements comprise a tunable promoter.

19. The system of claim 13 , wherein the at least one first polynucleotide comprises one or more polynucleotides encoding for multiple microcompartment proteins.

20. The system of any of claim 13 , wherein the at least one first polynucleotide comprises one or more polynucleotides encoding for PduA, B, J, K, N and U.

21. The system of claim 13 , wherein the one or more non-native toxic proteins comprise at least one non-native antimicrobial peptide.

22. The system of claim 13 , wherein the at least one non-native antimicrobial peptide is selected from cecropins, magainins, melittin, protegrins, and nisins.

23. The system of claim 13 , wherein the one or more non-native toxic proteins comprise one or more non-native proteases capable of reacting with a native membrane substrate.

24. The system of claim 13 , wherein the one or more non-native toxic proteins comprise one or more non-native proteases and one or more of non-native lysins.

25. The system of claim 13 , wherein the one or more non-native toxic proteins comprise chemotherapic non-native proteins.

26. A cell obtainable by the method of claim 1 .

27. A composition comprising one or more cells according to claim 26 together with a suitable vehicle.