Long-chain fatty acid transport across the outer membrane of E. coli requires the long-chain fatty acid transport protein FadL. FadL is hypothesized to contain at least two discreet domains: an N-terminal proximal domain involved in ligand binding and a C-terminal proximal domain involved in transport. Computer modeling suggests the amino terminal third of FadL is exposed on the surface of the outer membrane. The membrane-bound region of FadL is proposed to consist of a single a-helix and 8 antiparallel /3-sheets that may form a fatty acid-specific channel. This protein also serves as the primary receptor for the bacteriophage T2. We have identified a 28,500 Mr trypsin-resistant fragment within whole cells and isolated outer membranes. We presume this fragment represents the membrane-bound region of FadL. In an effort to define the region of FadL responsible for the binding of T2, membranes were isolated from afadL strain transformed with pN130 (fadL+) or pACYClT? (vector control) and subjected to proteolysis with trypsin. Membranes containing FadL were able to bind and inactivate T2 whereas membranes containing FadL which had been trypsinized or do not contain FadL were unable to bind T2. These results are consistent with the notion that the ami no-terminal third of FadL contains sequence elements required for the binding of bacteriophage T2. These data are in agreement with data generated using linker mutagenesis of fadL. Sequence analysis of the protease-resistant fragment is expected to confirm this postulate. Supported by NSF Grant MCB-9796006.
|Original language||English (US)|
|State||Published - 1998|
ASJC Scopus subject areas
- Molecular Biology