Present address: Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA.
Genome-wide screens: novel mechanisms in colicin import and cytotoxicity
Article first published online: 24 JUL 2009
© 2009 Blackwell Publishing Ltd
Volume 73, Issue 4, pages 571–585, August 2009
How to Cite
Sharma, O., Datsenko, K. A., Ess, S. C., Zhalnina, M. V., Wanner, B. L. and Cramer, W. A. (2009), Genome-wide screens: novel mechanisms in colicin import and cytotoxicity. Molecular Microbiology, 73: 571–585. doi: 10.1111/j.1365-2958.2009.06788.x
- Issue published online: 7 AUG 2009
- Article first published online: 24 JUL 2009
- Accepted 26 June, 2009.
Only two new genes (fkpA and lepB) have been identified to be required for colicin cytotoxicity in the last 25 years. Genome-wide screening using the ‘Keio collection’ to test sensitivity to colicins (col) A, B, D, E1, E2, E3, E7 and N from groups A and B, allowed identification of novel genes affecting cytotoxicity and provided new information on mechanisms of action. The requirement of lipopolysaccharide for colN cytotoxicity resides specifically in the lipopolysaccharide inner-core and first glucose. ColA cytotoxicity is dependent on gmhB and rffT genes, which function in the biosynthesis of lipopolysaccharide and enterobacterial common antigen. Of the tol genes that function in the cytoplasmic membrane translocon, colE1 requires tolA and tolR but not tolQ for activity. Peptidoglycan-associated lipoprotein, which interacts with the Tol network, is not required for cytotoxicity of group A colicins. Except for TolQRA, no cytoplasmic membrane protein is essential for cytotoxicity of group A colicins, implying that TolQRA provides the sole pathway for their insertion into/through the cytoplasmic membrane. The periplasmic protease that cleaves between the receptor and catalytic domains of colE7 was not identified, implying either that the responsible gene is essential for cell viability, or that more than one gene product has the necessary proteolysis function.