Structural insight into chain-length control and product specificity of pentaketide chromone synthase from Aloe arborescens.
The crystal structures of a wild-type and a mutant PCS, a novel plant type III polyketide synthase from a medicinal plant, Aloe arborescens, were solved at 1.6 A resolution. The crystal structures revealed that the pentaketide-producing wild-type and the octaketide-producing M207G mutant shared almost the same overall folding, and that the large-to-small substitution dramatically increases the volume of the polyketide-elongation tunnel by opening a gate to two hidden pockets behind the active site of the enzyme. The chemically inert active site residue 207 thus controls the number of condensations of malonyl-CoA, solely depending on the steric bulk of the side chain. These findings not only provided insight into the polyketide formation reaction, but they also suggested strategies for the engineered biosynthesis of polyketides.
Morita
Hiroyuki
H
Mitsubishi Kagaku Institute of Life Sciences (MITILS), 11 Minamiooya, Machida, Tokyo 194-8511, Japan.
Kondo
Shin
S
Oguro
Satoshi
S
Noguchi
Hiroshi
H
Sugio
Shigetoshi
S
Abe
Ikuro
I
Kohno
Toshiyuki
T
D000504:Aloe / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D002867:Chromones; D018360:Crystallography, X-Ray; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D048630:Polyketide Synthases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D016415:Sequence Alignment
D002867:Chromones; D048630:Polyketide Synthases