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| | {{STRUCTURE_1ee0| PDB=1ee0 | SCENE= }} | | {{STRUCTURE_1ee0| PDB=1ee0 | SCENE= }} |
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| - | '''2-PYRONE SYNTHASE COMPLEXED WITH ACETOACETYL-COA'''
| + | ===2-PYRONE SYNTHASE COMPLEXED WITH ACETOACETYL-COA=== |
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| - | ==Overview==
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| - | BACKGROUND: Polyketide synthases (PKSs) generate molecular diversity by utilizing different starter molecules and by controlling the final length of the polyketide. Although exploitation of this mechanistic variability has produced novel polyketides, the structural foundation of this versatility is unclear. Plant-specific PKSs are essential for the biosynthesis of anti-microbial phytoalexins, anthocyanin floral pigments, and inducers of Rhizobium nodulation genes. 2-Pyrone synthase (2-PS) and chalcone synthase (CHS) are plant-specific PKSs that share 74% amino acid sequence identity. 2-PS forms the triketide methylpyrone from an acetyl-CoA starter molecule and two malonyl-CoAs. CHS uses a p-coumaroyl-CoA starter molecule and three malonyl-CoAs to produce the tetraketide chalcone. Our goal was to elucidate the molecular basis of starter molecule selectivity and control of polyketide length in this class of PKS.Results: The 2.05 A resolution crystal structure of 2-PS complexed with the reaction intermediate acetoacetyl-CoA was determined by molecular replacement. 2-PS and CHS share a common three-dimensional fold, a set of conserved catalytic residues, and similar CoA binding sites. However, the active site cavity of 2-PS is smaller than the cavity in CHS. Of the 28 residues lining the 2-PS initiation/elongation cavity, four positions vary in CHS. Point mutations at three of these positions in CHS (T197L, G256L, and S338I) altered product formation. Combining these mutations in a CHS triple mutant (T197L/G256L/S338I) yielded an enzyme that was functionally identical to 2-PS.Conclusions: Structural and functional characterization of 2-PS together with generation of a CHS mutant with an initiation/elongation cavity analogous to 2-PS demonstrates that cavity volume influences the choice of starter molecule and controls the final length of the polyketide. These results provide a structural basis for control of polyketide length in other PKSs, and suggest strategies for further increasing the scope of polyketide biosynthetic diversity.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_11137815}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 11137815 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_11137815}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Polyketide synthase]] | | [[Category: Polyketide synthase]] |
| | [[Category: Thiolase fold]] | | [[Category: Thiolase fold]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 14:58:48 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 00:33:09 2008'' |
Revision as of 21:33, 30 June 2008
Template:STRUCTURE 1ee0
2-PYRONE SYNTHASE COMPLEXED WITH ACETOACETYL-COA
Template:ABSTRACT PUBMED 11137815
About this Structure
1EE0 is a Single protein structure of sequence from Gerbera hybrid cultivar. Full crystallographic information is available from OCA.
Reference
Structural control of polyketide formation in plant-specific polyketide synthases., Jez JM, Austin MB, Ferrer J, Bowman ME, Schroder J, Noel JP, Chem Biol. 2000 Dec;7(12):919-30. PMID:11137815
Page seeded by OCA on Tue Jul 1 00:33:09 2008
