Details

Autor(en) / Beteiligte

• Baldock, C
• Rafferty, J B
• Stuitje, A R
• Slabas, A R
• Rice, D W

Titel

The X-ray Structure of Escherichia coli Enoyl Reductase with Bound NAD at 2.1 Aa Resolution

Ist Teil von

• Journal of molecular biology, 1998-12, Vol.284 (5), p.1529-1546

Erscheinungsjahr

1998

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• Enoyl acyl carrier protein reductase catalyses the last reductive step of fatty acid biosynthesis, reducing an enoyl acyl carrier protein to an acyl-acyl carrier protein with NAD(P)H as the cofactor. The crystal structure of enoyl reductase (ENR) from Escherichia coli has been determined to 2.1 Aa resolution using a combination of molecular replacement and isomorphous replacement and refined using data from 10 Aa to 2.1 Aa to an R-factor of 0.16. The final model consists of the four subunits of the tetramer, wherein each subunit is composed of 247 of the expected 262 residues, and a NAD super(+) cofactor for each subunit of the tetramer contained in the asymmetric unit plus a total of 327 solvent molecules. There are ten disordered residues per subunit which form a loop near the nucleotide binding site which may become ordered upon substrate binding. Each monomer is composed of a seven-stranded parallel beta -sheet flanked on each side by three alpha -helices with a further helix lying at the C terminus of the beta -sheet. This fold is highly reminiscent of the Rossmann fold, found in many NAD(P)H-dependent enzymes. Analysis of the sequence and structure of ENR and comparisons with the family of short-chain alcohol dehydrogenases, identify a conserved tyrosine and lysine residue as important for catalytic activity. Modelling studies suggest that a region of the protein surface that contains a number of strongly conserved hydrophobic residues and lies adjacent to the nicotinamide ring, forms the binding site for the fatty acid substrate.