Structure of 1-aminocyclopropane-1-carboxylate synthase, a key enzyme in the biosynthesis of the plant hormone ethylene.
The 2.4 A crystal structure of the vitamin B6-dependent enzyme 1-aminocyclopropane-1-carboxylate (ACC) synthase is described. This enzyme catalyses the committed step in the biosynthesis of ethylene, a plant hormone that is responsible for the initiation of fruit ripening and for regulating many other developmental processes. ACC synthase has 15 % sequence identity with the well-studied aspartate aminotransferase, and a completely different catalytic activity yet the overall folds and the active sites are very similar. The new structure together with available biochemical data enables a comparative mechanistic analysis that largely explains the catalytic roles of the conserved and non-conserved active site residues. An external aldimine reaction intermediate (external aldimine with ACC, i.e. with the product) has been modeled. The new structure provides a basis for the rational design of inhibitors with broad agricultural applications.
Capitani
G
G
Structural Biology Division Biozentrum, University of Basel, Basel, CH-4056, Switzerland. capitani@biocfebs.unizh.ch
Hohenester
E
E
Feng
L
L
Storici
P
P
Kirsch
J F
JF
Jansonius
J N
JN
D000595:Amino Acid Sequence; D001219:Aspartate Aminotransferases / Q000737:chemistry; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis; D005030:Ethylenes / Q000096:biosynthesis*; D008190:Lyases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010944:Plants / Q000201:enzymology*; D011487:Protein Conformation
D004791:Enzyme Inhibitors; D005030:Ethylenes; C036216:ethylene; D001219:Aspartate Aminotransferases; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase