W0125

Structure of the Proline Dehydrogenase Domain of the Multifunctional PutA Flavoprotein. John Tanner, Dept. of Chemistry, Univ. of Missouri-Columbia, 125 Chemistry Bldg., Columbia, MO 65211 USA.

The PutA flavoprotein from Escherichia coli plays multiple roles in proline catabolism by functioning as a membrane-associated bi-functional enzyme and a transcriptional repressor of the proline utilization genes, while the human homologue of the PutA proline dehydrogenase (PRODH) domain plays critical roles in p53-mediated apoptosis and schizophrenia. I will present the 2.0 Å crystal structure of a 669-residue truncated form of PutA that exhibits both PRODH and DNA-binding activities, which represents the first structure of a PutA protein and the first structure of a PRODH enzyme from any organism. The structure is a domain-swapped dimer with each subunit comprising three domains: a helical dimerization arm, a 120-residue domain containing a three-helix bundle similar to that found in the helix-turn-helix superfamily of DNA-binding proteins, and a beta/alpha barrel PRODH domain with bound lactate inhibitor.

Analysis of the structure provides insight into the mechanism of proline oxidation to pyrroline-5-carboxylate, and functional studies of a mutant protein suggest the DNA-binding domain is located within the N-terminal 261 residues of E. coli PutA.

Reference: Lee et al., Nat. Struct. Biol. 2003 Feb;10(2):109-14.