1QJF

ISOPENICILLIN N SYNTHASE FROM ASPERGILLUS NIDULANS (Monocyclic Sulfoxide - Fe COMPLEX)

Summary for 1QJF

• Entry DOI: 10.2210/pdb1qjf/pdb
• Related: 1BK0 1QJE
• Descriptor: ISOPENICILLIN N SYNTHASE, SULFATE ION, 1-[(1S)-CARBOXY-2-(METHYLSULFINYL)ETHYL]-(3R)-[(5S)-5-AMINO-5-CARBOXYPENTANAMIDO]-(4R)-SULFANYLAZETIDIN-2-ONE, ... (5 entities in total)
• Functional Keywords: b-lactam antibiotic, monocyclic intermediate, oxygenase, penicillin biosynthesis, sulfoxide
• Biological source: Emericella nidulans (strain FGSC A4 / ATCC 38163 / CBS 112.46 / NRRL 194 / M139) (Aspergillus nidulans)
• Total number of polymer chains: 1
• Total formula weight: 38111.20

Authors

Rutledge, P.J.,Clifton, I.J.,Burzlaff, N.I.,Roach, P.L.,Adlington, R.M.,Baldwin, J.E. (deposition date: 1999-06-23, release date: 2000-06-29, Last modification date: 2024-05-08)

Primary citation

Burzlaff, N.I.,Rutledge, P.J.,Clifton, I.J.,Hensgens, C.M.H.,Pickford, M.,Adlington, R.M.,Roach, P.L.,Baldwin, J.E.
The Reaction Cycle of Isopenicillin N Synthase Observed by X-Ray Diffraction
Nature, 401:721-, 1999

PubMed Abstract: Isopenicillin N synthase (IPNS), a non-haem iron-dependent oxidase, catalyses the biosynthesis of isopenicillin N (IPN), the precursor of all penicillins and cephalosporins. The key steps in this reaction are the two iron-dioxygen-mediated ring closures of the tripeptide delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine (ACV). It has been proposed that the four-membered beta-lactam ring forms initially, associated with a highly oxidized iron(iv)-oxo (ferryl) moiety, which subsequently mediates closure of the five-membered thiazolidine ring. Here we describe observation of the IPNS reaction in crystals by X-ray crystallography. IPNS Fe2+ substrate crystals were grown anaerobically, exposed to high pressures of oxygen to promote reaction and frozen, and their structures were elucidated by X-ray diffraction. Using the natural substrate ACV, this resulted in the IPNS x Fe2+ x IPN product complex. With the substrate analogue, delta-(L-alpha-aminoadipoyl)-L-cysteinyl-L-S-methylcysteine (ACmC) in the crystal, the reaction cycle was interrupted at the monocyclic stage. These mono- and bicyclic structures support our hypothesis of a two-stage reaction sequence leading to penicillin. Furthermore, the formation of a monocyclic sulphoxide product from ACmC is most simply explained by the interception of a high-valency iron-oxo species.

PubMed: 10537113
DOI: 10.1038/44400

Experimental method

X-RAY DIFFRACTION (1.4 Å)