PMID: 19004827 , Related PDB ids: 2VNE, 2VQ5

Authors:

Ilari A, Franceschini S, Bonamore A, Arenghi F, Botta B, Macone A, Pasquo A, Bellucci L, Boffi A

Title:

Structural basis of enzymatic (S)-norcoclaurine biosynthesis.

Journal:

J Biol Chem. 2009 Jan 9;284(2):897-904. Epub 2008 Nov 12.

Abstract:

The enzyme norcoclaurine synthase (NCS) catalyzes the stereospecific Pictet-Spengler cyclization between dopamine and 4-hydroxyphenylacetaldehyde, the key step in the benzylisoquinoline alkaloid biosynthetic pathway. The crystallographic structure of norcoclaurine synthase from Thalictrum flavum in its complex with dopamine substrate and the nonreactive substrate analogue 4-hydroxybenzaldehyde has been solved at 2.1A resolution. NCS shares no common features with the functionally correlated "Pictet-Spenglerases" that catalyze the first step of the indole alkaloids pathways and conforms to the overall fold of the Bet v1-like protein. The active site of NCS is located within a 20-A-long catalytic tunnel and is shaped by the side chains of a tyrosine, a lysine, an aspartic, and a glutamic acid. The geometry of the amino acid side chains with respect to the substrates reveals the structural determinants that govern the mechanism of the stereoselective Pictet-Spengler cyclization, thus establishing an excellent foundation for the understanding of the finer details of the catalytic process. Site-directed mutations of the relevant residues confirm the assignment based on crystallographic findings.