Crystal Structure of the Long-Chain Fatty Acid Transporter FadL
The mechanisms by which hydrophobic molecules, such as long-chain fatty acids, enter cells are poorly understood. In Gram-negative bacteria, the lipopolysaccharide layer in the outer membrane is an efficient barrier for fatty acids and aromatic hydrocarbons destined for biodegradation. We report crystal structures of the long-chain fatty acid transporter FadL from Escherichia coli at 2.6 and 2.8 angstrom resolution. FadL forms a 14-stranded β barrel that is occluded by a central hatch domain. The structures suggest that hydrophobic compounds bind to multiple sites in FadL and use a transport mechanism that involves spontaneous conformational changes in the hatch.
© 2004 American Association for the Advancement of Science. 4 March 2004; accepted 4 May 2004. We would like to thank M. Becker and L. Berman for support at beamline X25 at the National Synchrotron Light Source (Brookhaven National Laboratory), and C. Ogata and M. Capel for help at beamline 8BM at the Advanced Photon Source (Northeastern Collaborative Access team). We also would like to thank S. C. Harrison for in-house x-ray generator access and L. S. Wolff for performing fatty acid transport and binding experiments. P.N.B. received support from the NSF. W.M.C. is supported by a fellowship from the Damon Runyon Cancer Research Foundation. T.A.R is a Howard Hughes Medical Institute investigator. Coordinates and structure factors have been deposited in the Protein Data Bank with accession codes 1T16 (monoclinic crystal form) and 1T1L (hexagonal crystal form).
Supplemental Material - van_den_Berg_SOM.pdf