Isopenicillin N synthase; part of the gene cluster that mediates the biosynthesis of penicillin, the world's most important antibiotic (PubMed:1368505). The first step of the pathway is performed by the trimodular NRPS acvA that produces the tripeptide N-[(5S)-5-amino-5-carboxypentanoyl]-L-cysteinyl-D-valine (LLD-ACV or ACV) via condensation of the 3 residues L-2-aminoadipate, L-cysteine and L-valine (PubMed:9266851, PubMed:9355751, PubMed:19686863, PubMed:21889568). The precursor amino acids for penicillin biosynthesis are withdrawn from the vacuolar amino acid pool by the MFS-type transporter penV (PubMed:8416970, PubMed:22777282). Each of the constituent amino acids of the tripeptide acv are activated as aminoacyl-adenylates with peptide bonds formed through the participation of amino acid thioester intermediates (PubMed:9266851, PubMed:21889568). The tripeptide ACV is then cyclized to form isopenicillin N (IPN) by the isopenicillin N synthase ipnA that forms the beta-lactam nucleus (PubMed:1368505, PubMed:1369045, PubMed:1588566). Finally, the alpha-aminoadipyl side chain is exchanged for phenylacetic acid by the isopenicillin N acyltransferase aatA to yield penicillin (PubMed:2120195, PubMed:2110531, PubMed:1368505). This step occurs in the peroxisomal matrix and the penM and paaT transporters are involved in the isopenicillin N and phenylacetic acid import into the peroxisome, respectively (PubMed:23053082, PubMed:24480587). N-[(5S)-5-amino-5-carboxypentanoyl]-L-cysteinyl-D-valine + O2 = 2 H2O + isopenicillin N Binds 1 Fe(2+) ion per subunit. Antibiotic biosynthesis; penicillin G biosynthesis; penicillin G from L-alpha-aminoadipate and L-cysteine and L-valine: step 2/3. Expression is repressed by glucose (PubMed:3096965). The transcription factor rfx1 controls penicillin biosynthesis through the regulation of the acvA, ipnA and aatA transcription (PubMed:22960281). Expression is also controlled by the transcription factor pacC that specifically recognizes the 5'-GCCARG-3' sequence in the promoter (PubMed:8736532). Belongs to the iron/ascorbate-dependent oxidoreductase family.