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Depletion of apolipoprotein N-acyltransferase causes mislocalization of outer membrane lipoproteins in Escherichia coli.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2005 Jan 14; Vol. 280 (2), pp. 974-83. Date of Electronic Publication: 2004 Oct 28. - Publication Year :
- 2005
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Abstract
- Lipoproteins in Gram-negative Enterobacteriaceae carry three fatty acids on the N-terminal cysteine residue, two as a diacylglyceride and one through an N-linkage following signal peptide cleavage. Most lipoproteins are anchored in the outer membrane, facing the periplasm, but some lipoproteins remain in the plasma membrane, depending on the amino acid at position +2, immediately after the fatty-acylated cysteine. In vitro, the last step in lipoprotein maturation, N-acylation of apolipoproteins by the plasma membrane apolipoprotein N-acyltransferase (Lnt), is necessary for efficient recognition of outer membrane lipoproteins by the Lol system, which transports them from the plasma to the outer membrane (Fukuda, A., Matsuyama, S.-I., Hara, T., Nakayama, J., Nagasawa, H., and Tokuda, H. (2002) J. Biol. Chem. 277, 43512-43518). To study the role of Lnt in vivo, we constructed a conditional lnt mutant of Escherichia coli. The apo-form of peptidoglycan-anchored major lipoprotein (Lpp) and two other outer membrane lipoproteins accumulated in the plasma membrane when lnt expression was reduced. We also found that Lnt is an essential protein in E. coli and that the lethality is partially because of the retention of apoLpp in the plasma membrane. Topology mapping of Lnt with beta-galactosidase and alkaline phosphatase fusions indicated the presence of six membrane-spanning segments. The lnt gene in a mutant of Salmonella enterica displaying thermosensitive Lnt activity (Gupta, S. D., Gan, K., Schmid, M. B., and Wu, H. C. (1993) J. Biol. Chem. 268, 16551-16556) was found to carry a mutation causing a single glutamate to lysine substitution at a highly conserved position in the last predicted periplasmic loop of the protein.
- Subjects :
- Acyltransferases genetics
Acyltransferases metabolism
Apoproteins metabolism
Cell Membrane metabolism
Escherichia coli cytology
Escherichia coli enzymology
Escherichia coli genetics
Genes, Essential genetics
Genetic Complementation Test
Mutation genetics
Periplasmic Binding Proteins metabolism
Protein Transport
Salmonella enterica genetics
Acyltransferases deficiency
Bacterial Outer Membrane Proteins metabolism
Escherichia coli metabolism
Escherichia coli Proteins metabolism
Lipoproteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 280
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 15513925
- Full Text :
- https://doi.org/10.1074/jbc.M411059200