Nonribosomal peptide synthetase; part of the gene cluster that mediates the biosynthesis of aspulvinones (PubMed:29305695, PubMed:23841722, PubMed:28791090). The nonribosomal peptide synthetase apvA is responsible for the production of aspulvinone E, the core structure of aspulvinones (PubMed:29305695, PubMed:23841722, PubMed:28791090). ApvA first activates 4-hydroxyphenylpyruvate (HPPA) through its A domain to AMP-HPPA (Probable). The HPPA unit is then loaded to the T domain and eventually transferred to the TE domain (Probable). Upon loading of another HPPA unit to the T domain, the TE domain promotes the enolate formation on the unit attached (Probable). The next step involves head to tail Claisen condensation, followed by the keto-enol tautermerization and a nucleophilic attack on the carbonyl carbon to yield the furanone partial structure (Probable). A spontaneous oxidation at the beta-carbon of the thioester might occur in aerobic condition (Probable). The TE domain then catalyzes the hydrolysis of the thioester, followed by spontaneous decarboxylation, dehydroxylation and keto-enol tautermerization to give the aspulvinone core (Probable). Aspulvinone E is highly unstable and converted to isoaspulvinone E in the presence of light (PubMed:29305695). The structural diversity of the aspulvinones suggests that other tailoring enzymes are involved and have still to be identified (Probable). 2 3-(4-hydroxyphenyl)pyruvate = aspulvinone E + H2O Secondary metabolite biosynthesis. ApvA specifically produces aspulvinone E in hyphea, in contrast to melA which produces aspulvinone E in conidia where it is converted to UV-protective Asp-melanin. ApvA has an A-T-TE domain architecture (Probable). The adenylation (A) domain recognizes and activates the aryl acid substrates, and loads them onto the thiolation (T) domain (Probable). The thioesterase (TE) domain shares the missing condensation (C) domain function, and is responsible for condensation and final product release (Probable). Abolishes the production of aspulvinone E in hyphae, but not in conidia. Belongs to the NRP synthetase family.