PMID:12823819

Citation	Narita, S, Kanamaru, K, Matsuyama, S and Tokuda, H (2003) A mutation in the membrane subunit of an ABC transporter LolCDE complex causing outer membrane localization of lipoproteins against their inner membrane-specific signals. Mol. Microbiol. 49:167-77
Abstract	Lipoproteins in Gram-negative bacteria are anchored to the inner or outer membrane via fatty acids attached to the N-terminal cysteine. The residue at position 2 determines the membrane specificity. An ATP binding cassette transporter LolCDE complex releases lipoproteins with residues other than aspartate at position 2 from the inner membrane, whereas those with aspartate at position 2 are rejected by LolCDE and therefore remain in the inner membrane. For further understanding of this rejection mechanism, a novel strategy was developed to select mutants in which lipoproteins with aspartate at position 2 are released. The isolated mutants carried an alanine to proline mutation at position 40 of LolC, a membrane subunit of the LolCDE complex. A significant portion of an inner membrane lipoprotein, L10P(DQ), was localized to the outer membrane when the LolC mutant was expressed. Periplasmic chaperone LolA formed a complex with the released L10P(DQ), which was subsequently incorporated into the outer membrane in a LolB-dependent manner, indicating that neither LolA nor LolB rejects lipoproteins with aspartate at position 2. The amount of the LolC mutant co-purified with LolD and LolE after membrane solubilization was reduced significantly. Taken together, these results indicate that the mutation causes destabilization of the LolCDE complex and concomitantly prevents the accurate recognition of lipoprotein-sorting signals.
Links	PubMed
Keywords	ATP-Binding Cassette Transporters/genetics; ATP-Binding Cassette Transporters/metabolism; Amino Acid Sequence; Cell Division; Cell Membrane/metabolism; Escherichia coli/cytology; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Lipoproteins/metabolism; Macromolecular Substances; Molecular Chaperones/metabolism; Molecular Sequence Data; Mutation; Protein Sorting Signals; Protein Subunits/genetics; Protein Subunits/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ECOLI:LOLC		GO:0089705: protein localization to outer membrane	ECO:0000315:		P		Figure 6, panel B. Mutant LolC(A40P)DE results in AcrA (an inner membrane protein) being localized to the outer membrane.	complete CACAO 10141
ECOLI:LOLC	involved_in	GO:0089705: protein localization to outer membrane	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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