Nonribosomal peptide synthetase that mediates the biosynthesis of phenguignardic acid (PubMed:26851300, PubMed:29305695). PngA alone is sufficient for phenguignardic acid synthesis (PubMed:26851300, PubMed:29305695). PngA first activates phenylpyruvic acid (PPA) through its A domain to AMP-PPA (PubMed:26851300, PubMed:29305695). The PPA unit is then loaded to the T domain and eventually transferred to the TE domain (PubMed:26851300, PubMed:29305695). Another PPA unit is then loaded onto the T domain (PubMed:26851300, PubMed:29305695). The TE domain likely promotes the enolate formation on the attached unit, followed by a nucleophilic attack on the carbonyl to yield an ether linkage between the two units (PubMed:26851300, PubMed:29305695). Finally, the TE domain probably catalyzes a similar reaction to give the cyclized dioxolanone core and releases phenguignardic acid (PubMed:26851300, PubMed:29305695). 2 3-phenylpyruvate + H(+) = H2O + phenguignardate AtrA has a 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). Belongs to the NRP synthetase family.