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Characterization of Interactions and Phospholipid Transfer between Substrate Binding Proteins of the OmpC-Mla System.
- Source :
-
Biochemistry [Biochemistry] 2019 Jan 15; Vol. 58 (2), pp. 114-119. Date of Electronic Publication: 2018 Oct 08. - Publication Year :
- 2019
-
Abstract
- The outer membrane (OM) of Gram-negative bacteria is a permeability barrier that impedes the entry of external insults, such as antibiotics and bile salts. This barrier function depends critically on the asymmetric lipid distribution across the bilayer, with lipopolysaccharides (LPS) facing outside and phospholipids (PLs) facing inside. In Escherichia coli, the OmpC-Mla system is believed to maintain OM lipid asymmetry by removing surface exposed PLs and shuttling them back to the inner membrane (IM). How proteins in the pathway interact to mediate PL transport across the periplasm is not known. Evidence for direct transfer of PLs between these proteins is also lacking. In this study, we mapped the interaction surfaces between the two PL-binding proteins, MlaC and MlaD, using site-specific in vivo photo-cross-linking, and obtained a physical picture for how these proteins may transfer PLs. Furthermore, we demonstrated using purified proteins that MlaD spontaneously transfers PLs to MlaC, suggesting that the latter has a higher affinity for PLs. Our work provides insights into the mechanism of bacterial intermembrane lipid transport important for the maintenance of OM lipid asymmetry.
- Subjects :
- Biological Transport
Chromatography, Thin Layer
Cross-Linking Reagents
Escherichia coli Proteins chemistry
Membrane Proteins chemistry
Membrane Transport Proteins chemistry
Phospholipid Transfer Proteins chemistry
Phospholipid Transfer Proteins metabolism
Porins metabolism
Protein Interaction Maps
Tandem Mass Spectrometry
Escherichia coli Proteins metabolism
Membrane Proteins metabolism
Membrane Transport Proteins metabolism
Phospholipids metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1520-4995
- Volume :
- 58
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 30284446
- Full Text :
- https://doi.org/10.1021/acs.biochem.8b00897