A colicin M derivative containing the lipoprotein signal sequence is secreted and renders the colicin M target accessible from inside the cells
✍ Scribed by Tobias Ölschläger
- Book ID
- 104680436
- Publisher
- Springer
- Year
- 1991
- Tongue
- English
- Weight
- 963 KB
- Volume
- 156
- Category
- Article
- ISSN
- 0302-8933
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✦ Synopsis
Colicin M is only released in very low amounts by cells harbouring this plasmid encoded colicin, due to the lack of a release (lysis) protein. A fusion gene (lpp'cma) was constructed which determined two proteins: Lpp'-Cma composed of the signal sequence of the murein lipoprotein (Lpp) and colicin M (Cma), and unaltered colicin M. Cells expressing the fusion gene released 50% of the total colicin M into the culture medium, compared to 1% found in the medium of cells synthesizing only colicin M. The release resulted from partial cell lysis caused by colicin M since a colicin M tolerant strain remained unaffected. Lpp'-Cma thus mimics phenotypically the action of colicin release proteins but displays a different lysis mechanism. In strains defective in components of the colicin M uptake system, Lpp'-Cma caused lysis as effectively as in uptake proficient strains. Apparently, Lpp'-Cma renders the colicin M target site accessible from inside the cell which stands in contrast to the action of colicin M which is only bactericidal when provided from outside.