1YQD

Sinapyl Alcohol Dehydrogenase complexed with NADP+

Summary for 1YQD

• Entry DOI: 10.2210/pdb1yqd/pdb
• Descriptor: sinapyl alcohol dehydrogenase, ZINC ION, NADP NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE, ... (6 entities in total)
• Functional Keywords: lignin, monolignol, oxidoreductase, zinc-dependent, plant defense, biosynthesis, substrate inhibition, medium-chain dehydrogense/reductase
• Biological source: Populus tremuloides (quaking aspen)
• Total number of polymer chains: 2
• Total formula weight: 80907.10

Authors

Bomati, E.K.,Noel, J.P. (deposition date: 2005-02-01, release date: 2005-07-12, Last modification date: 2024-04-03)

Primary citation

Bomati, E.K.,Noel, J.P.
Structural and Kinetic Basis for Substrate Selectivity in Populus tremuloides Sinapyl Alcohol Dehydrogenase.
Plant Cell, 17:1598-1611, 2005

PubMed Abstract: We describe the three-dimensional structure of sinapyl alcohol dehydrogenase (SAD) from Populus tremuloides (aspen), a member of the NADP(H)-dependent dehydrogenase family that catalyzes the last reductive step in the formation of monolignols. The active site topology revealed by the crystal structure substantiates kinetic results indicating that SAD maintains highest specificity for the substrate sinapaldehyde. We also report substantial substrate inhibition kinetics for the SAD-catalyzed reduction of hydroxycinnamaldehydes. Although SAD and classical cinnamyl alcohol dehydrogenases (CADs) catalyze the same reaction and share some sequence identity, the active site topology of SAD is strikingly different from that predicted for classical CADs. Kinetic analyses of wild-type SAD and several active site mutants demonstrate the complexity of defining determinants of substrate specificity in these enzymes. These results, along with a phylogenetic analysis, support the inclusion of SAD in a plant alcohol dehydrogenase subfamily that includes cinnamaldehyde and benzaldehyde dehydrogenases. We used the SAD three-dimensional structure to model several of these SAD-like enzymes, and although their active site topologies largely mirror that of SAD, we describe a correlation between substrate specificity and amino acid substitution patterns in their active sites. The SAD structure thus provides a framework for understanding substrate specificity in this family of enzymes and for engineering new enzyme specificities.

PubMed: 15829607
DOI: 10.1105/tpc.104.029983

Experimental method

X-RAY DIFFRACTION (1.65 Å)