Structure of L-arabinose-binding protein from Escherichia coli at 5 A resolution and preliminary results at 3.5 A.

The three-dimensional crystal structure of the L-arabinose-binding protein from E. coli, an essential component in the active transport of L-arabinose, has been solved at 5 A resolution using the method of multiple isomorphous replacement. Five heavy atom derivatives were used. A preliminary 3.5 A electron density map has also been calculated. The results indicate that the molecule is ellipsoidal with approximate dimensions 68 A X 38 A X 30 A. Two similar domains within the molecule (which is a single polypeptide chain) are related by an approximate noncrystallographic rotation-translation axis. This relationship involves approximately 20% of the structure.