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Structure of a cephalosporin synthase
K Valegård1, A C van Scheltinga, M D Lloyd
1Department of Biochemistry, Uppsala University, Sweden.
Nature
|September 2, 1998
Summary
Researchers elucidated the structure of deacetoxycephalosporin C synthase (DAOCS), an iron-dependent enzyme crucial for cephalosporin antibiotic biosynthesis. This provides insights into controlled ferryl formation mechanisms in mononuclear ferrous enzymes.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Penicillins and cephalosporins are vital antibiotics produced via fermentation due to complex chemical synthesis.
- Fe(II)-dependent oxidases/oxygenases, like isopenicillin N synthase (IPNS) and deacetoxycephalosporin C synthase (DAOCS), are key in their biosynthesis.
- DAOCS expands the penicillin nucleus to the cephalosporin nucleus, utilizing a unique ferryl intermediate formation pathway involving 2-oxoglutarate.
Purpose of the Study:
- To determine the first crystal structure of a 2-oxoacid-dependent oxygenase, specifically DAOCS.
- To elucidate the structural basis for ferryl intermediate formation in DAOCS catalysis.
- To propose a mechanism for ferryl formation in mononuclear ferrous enzymes.
Main Methods:
- X-ray crystallography was employed to obtain high-resolution structures.
- Structures were determined for apo-DAOCS, the enzyme complexed with Fe(II), and with Fe(II) and 2-oxoglutarate.
- Merohedrally twinned crystals were utilized for structure determination.
Main Results:
- The crystal structures of DAOCS in various states (apo, Fe(II)-bound, Fe(II) and 2-oxoglutarate-bound) were successfully obtained.
- These structures provide detailed insights into the enzyme's active site and cofactor interactions.
- A model for ferryl formation, based on the obtained structures, was proposed.
Conclusions:
- The study presents the first structural evidence for a 2-oxoacid-dependent oxygenase, DAOCS.
- The findings offer a mechanistic understanding of controlled ferryl formation, common in mononuclear ferrous enzymes.
- This work contributes to the broader understanding of enzyme catalysis and antibiotic biosynthesis pathways.