Nonribosomal peptide synthetase; part of the gene cluster that mediates the biosynthesis of penicillin, the world's most important antibiotic (PubMed:1368505, PubMed:2120195, PubMed:2110531). 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 The precursor amino acids for penicillin biosynthesis are withdrawn from the vacuolar amino acid pool by the MFS-type transporter penV (PubMed:8416970, PubMed:22777282).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). H2O + isopenicillin N + phenylacetyl-CoA = CoA + H(+) + L-2-aminoadipate + penicillin G Antibiotic biosynthesis; penicillin G biosynthesis; penicillin G from L-alpha-aminoadipate and L-cysteine and L-valine: step 3/3. The active form of the enzyme results from processing of the 40-kDa monomeric precursor to a heterodimer containing subunits of 11 and 29 kDa. The unprocessed preprotein is translocated inside peroxisomes and regulates its self-processing. The transcription factor rfx1 controls penicillin biosynthesis through the regulation of the acvA, ipnA and aatA transcription. The pre-AAT protein is synthesized as 40 kDa precursor which is then self-processed into an 11 kDa (protein A) and a 29 kDa (protein B). The B protein carries AAT activity. Belongs to the peptidase C45 family.