The excC and excD genes of Escherichia coli K-12 encode the peptidoglycan-associated lipoprotein (PAL) and the TolQ protein, respectively
The tol genes of Escherichia coli K-12 are involved in the import of macromolecules such as group A colicins or filamentous phage DNA, and in the maintenance of cell envelope integrity (for a review, see Webster, 1991). Four genes, tolQRAB, located at min 17 in the genetic map have been identified and sequenced (Sun & Webster, 1987; Levengood & Webster, 1989). Mutants altered in the tolQRA genes are tolerant to groupA colicins and resistant to filamentous phages while mutants in the tolB gene are only tolerant to colicin A, E2 and E3. In addition, tol mutants are hypersensitive to drugs and release most of the periplasmic proteins into the extracellular medium.
KeywordsHydrolysis Glycerol Codon Glycine Cysteine
Unable to display preview. Download preview PDF.
- Braun V (1989) The structurally related exbB and tolQ genes are interchangeable in conferring tonB-dependent colicin, bacteriophage and albomycin sensitivity. J Bacteriol 171:2458–2465Google Scholar
- Fognini-Lefebvre N, Portalier R (1984) Isolation and preliminary characterization of beta-lactamase excretory mutants of Escherichia coli K-12. FEMS Microbiol Lett 21:323–328Google Scholar
- Lazzaroni JC, Portalier R (1992) The excC gene ofEscherichia coli K-12 re quired for the cell envelope integrity encodes the peptidoglycan-associated lipoprotein (PAL). Mol Microbiol, in pressGoogle Scholar
- Regue M, Wu HC (1988) Synthesis and export of lipoproteins in bacteria. In: Das RC, Robbins PW, (eds) Protein transfer and organelle biogenesis Academic Press Inc, San Diego, pp 587–606Google Scholar