Isopenicillin N synthase with AC-D-S-methyl-3R-methylcysteineIsopenicillin N synthase with AC-D-S-methyl-3R-methylcysteine

Structural highlights

2y6f is a 1 chain structure with sequence from Aspergillus nidulans. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 1.79Å
Ligands:, ,
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

IPNA_EMENI Isopenicillin N synthase; part of the gene cluster that mediates the biosynthesis of penicillin, the world's most important antibiotic (PubMed:3319778, PubMed:11755401). IpnA catalyzes the cyclization of the tripeptide N-[(5S)-5-amino-5-carboxypentanoyl]-L-cysteinyl-D-valine (LLD-ACV or ACV) to form isopenicillin N (IPN) that contains the beta-lactam nucleus (PubMed:3319778, PubMed:11755401, PubMed:28703303). The penicillin biosynthesis occurs via 3 enzymatic steps, the first corresponding to the production of the tripeptide N-[(5S)-5-amino-5-carboxypentanoyl]-L-cysteinyl-D-valine (LLD-ACV or ACV) by the NRPS acvA. The tripeptide ACV is then cyclized to isopenicillin N (IPN) by the isopenicillin N synthase ipnA that forms the beta-lactam nucleus. Finally, the alpha-aminoadipyl side chain is exchanged for phenylacetic acid by the isopenicillin N acyltransferase penDE to yield penicillin in the peroxisomal matrix (By similarity).[UniProtKB:P08703][1] [2] [3]

Publication Abstract from PubMed

Isopenicillin N synthase (IPNS) catalyses the synthesis of isopenicillin N (IPN), the biosynthetic precursor to penicillin and cephalosporin antibiotics. IPNS is a non-heme iron(II) oxidase that mediates the oxidative cyclisation of the tripeptide delta-L-alpha-aminoadipoyl-L-cysteinyl-D-valine (ACV) to IPN with a concomitant reduction of molecular oxygen to water. Solution-phase incubation experiments have shown that, although IPNS can turn over analogues with a diverse range of hydrocarbon side chains in the third (valinyl) position of its substrate, the enzyme is much less tolerant of polar residues in this position. Thus, although IPNS converts delta-L-alpha-aminoadipoyl-L-cysteinyl-D-isoleucine (ACI) and AC-D-allo-isoleucine (ACaI) to penam products, the isosteric sulfur-containing peptides AC-D-thiaisoleucine (ACtI) and AC-D-thia-allo-isoleucine (ACtaI) are not turned over. To determine why these peptides are not substrates, we crystallized ACtaI with IPNS. We report the synthesis of ACtaI and the crystal structure of the IPNS:Fe(II) :ACtaI complex to 1.79 A resolution. This structure reveals direct ligation of the thioether side chain to iron: the sulfide sulfur sits 2.66 A from the metal, squarely in the oxygen binding site. This result articulates a structural basis for the failure of IPNS to turn over these substrates.

Isopenicillin N Synthase Binds delta-(L-alpha-Aminoadipoyl)-L-Cysteinyl-D-Thia-allo-Isoleucine through both Sulfur Atoms.,Clifton IJ, Ge W, Adlington RM, Baldwin JE, Rutledge PJ Chembiochem. 2011 Aug 16;12(12):1881-5. doi: 10.1002/cbic.201100149. Epub, 2011 Jun 15. PMID:21678539[4]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

See Also

References

  1. Ogle JM, Clifton IJ, Rutledge PJ, Elkins JM, Burzlaff NI, Adlington RM, Roach PL, Baldwin JE. Alternative oxidation by isopenicillin N synthase observed by X-ray diffraction. Chem Biol. 2001 Dec;8(12):1231-7. PMID:11755401
  2. McNeill LA, Brown TJN, Sami M, Clifton IJ, Burzlaff NI, Claridge TDW, Adlington RM, Baldwin JE, Rutledge PJ, Schofield CJ. Terminally Truncated Isopenicillin N Synthase Generates a Dithioester Product: Evidence for a Thioaldehyde Intermediate during Catalysis and a New Mode of Reaction for Non-Heme Iron Oxidases. Chemistry. 2017 Sep 18;23(52):12815-12824. doi: 10.1002/chem.201701592. Epub 2017, Aug 21. PMID:28703303 doi:http://dx.doi.org/10.1002/chem.201701592
  3. Ramon D, Carramolino L, Patino C, Sanchez F, Penalva MA. Cloning and characterization of the isopenicillin N synthetase gene mediating the formation of the beta-lactam ring in Aspergillus nidulans. Gene. 1987;57(2-3):171-81. doi: 10.1016/0378-1119(87)90120-x. PMID:3319778 doi:http://dx.doi.org/10.1016/0378-1119(87)90120-x
  4. Clifton IJ, Ge W, Adlington RM, Baldwin JE, Rutledge PJ. Isopenicillin N Synthase Binds delta-(L-alpha-Aminoadipoyl)-L-Cysteinyl-D-Thia-allo-Isoleucine through both Sulfur Atoms. Chembiochem. 2011 Aug 16;12(12):1881-5. doi: 10.1002/cbic.201100149. Epub, 2011 Jun 15. PMID:21678539 doi:10.1002/cbic.201100149

2y6f, resolution 1.79Å

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