Heterologous expression of extremophile heat shock proteins and chaperones in microorganisms to increase tolerance to toxic compounds
The invention provides methods and compositions for increasing tolerance of microorganisms to toxic agents, such as solvents; and for increasing production of solvents from solvent-generating microorganisms. The methods comprise engineering a microorganism of interest to express a heterologous heat-shock protein/chaperone, e.g., Group II chaperonin or a prefoldin such as γ-prefoldin, where the heterologous protein is from an extremophile, such as an archaean.
1. A method of increasing the tolerance of a microorganism to a toxic compound, the method comprising introducing an expression cassette comprising a nucleic acid sequence encoding a heterologous γ prefoldin from an extremophile into the microorganism and expressing the nucleic acid sequence to produce γ-prefoldin, whereupon the microorganism has increased tolerance when exposed to the toxic compound.
2. The method of claim 1 , wherein the γ prefoldin is from an Archaea species.
3. The method of claim 2 , wherein the Archaea sp. is a Methanocaldococcus species.
4. The method of claim 1 , wherein the extremophile is a species of bacteria, an Archaeal species, a species of yeast, or a cyanobacteria species.
5. The method of claim 1 , wherein the microorganism is a species of bacteria, a species of yeast, a species of filamentous fungus, a species of cyanobacteria, or an Archaeal species.
6. The method of claim 5 , wherein the bacteria is Clostridium, Escherichia coli ( E. coli ), or Zymomonas mobilis.
7. The method of claim 6 , wherein the E. coli comprises heterologous genes that encode solvent-producing enzymes.
8. The method of claim 1 , wherein the toxic compound is an organic solvent.
9. The method of claim 1 , wherein the toxic compound is selected from the group consisting of ethanol, butanol, a five-carbon alcohol, a terpene, an alkane, a fatty acid, a fatty acid ester, and a ketone.
10. The method of claim 1 , wherein the nucleic acid sequence in operably linked to an inducible promoter.
11. The method of claim 10 , wherein the inducible promoter is a solvent inducible promoter.
12. The method of claim 1 , wherein the nucleic acid sequence in operably linked to a constitutive promoter.
13. The method of claim 1 , wherein the toxic agent to which the microorganism is exposed is produced by the microorganism.
14. A method of increasing the resistance of a microorganism to lethal heat, the method comprising introducing an expression cassette comprising a heterologous nucleic acid encoding γ prefoldin into the microorganism.
15. The method of claim 14 , wherein the γ prefoldin is from an Archaea species.
16. The method of claim 15 , wherein the Archaea sp. is a Methanocaldococcus species.