| 摘要 |
PURPOSE: To obtain a new mutant strain which has a mutant gene that can stably hold an unstable protein expressed in the cell bodies of Escherichia coil and can inhibit an extraneous useful protein expressed in the cell bodies from being decomposed, thus is useful as versatile host for expression of extraneous protein. CONSTITUTION: This new Escherichia coil mutant has a mutant gene that can keep an unstable protein such as an extraneous protein expressed in the cell bodies stable, since a heat-shock transcription factor σ<32> is stabilized by transducing a mutant gene having mutation in the plsX gene. Thus, the extraneous useful protein expressed in the cell bodies can be prevented from intracellular decompositions, and the mutant can be used as a versatile host for protein expression. This mutant is obtained by culturing E. coli MC4100 overnight and treating it with λ 1098 phage solution and selecting a pls X gene mutant strain with high σ<32> content from the colony. Or an existing E. coli strain is infected with a phage solution prepared from a protease-deficient strain and select a double mutant strain of Lon and Clp protease genes. |
