Publication

Abstract : The outer membrane protein FadL (product of the fadL gene) of Escherichia coli is required for the specific binding and transport of exogenous long-chain fatty acids prior to metabolic utilization. The carboxyl end of FadL has been proposed to play a crucial role by facilitating the transport of long-chain fatty acids. In an attempt to define specific amino acid residues within carboxyl region of FadL essential for activity, a series of deletion and point mutations within the 3' end of the fadL+ gene have been constructed and characterized. These fadL mutants were classified into three categories based on functional properties attributable to the altered FadL proteins: (i) those that had essentially wild-type levels of long-chain fatty acid binding and transport, (ii) those that had wild-type levels of long-chain fatty acid binding but were defective in transport, and (iii) those that were defective for both long-chain fatty acid binding and transport. These findings demonstrate that amino acid residues Phe448, Pro428, Val410, and Ser397 are required for optimal levels of long-chain fatty acid transport and that amino acid residues Pro428 and Val410 are essential for long-chain fatty acid binding.