Non-canonical nonribosomal peptide synthetase; part of the lnb gene cluster that mediates the biosynthesis of diastereomeric piperazines. Lna and lnb clusters encode sets of enzymes that produce overlapping sets of previously undescribed metabolites such as piperazinomycin-like metabolites or morpholine (PubMed:23281040). The lna and lnb biosynthetic pathways appear to be part of a signaling network that controls the formation of sclerotia, a resilient overwintering structure (PubMed:23281040). One primary function of the non-canonical nonribosomal peptide synthetases lnaA and lnbA consists in the reduction of L-tyrosine (PubMed:23281040). The presence in the clusters of tailoring enzymes such as the oxidoreductases lnaB, lnbB, lnaE or lnbE, as well as of the cytochrome P450 monooxygenases lnaC, lnaD, or lnbC, might explain formation of various diastereomeric piperazines (PubMed:23281040). AMP + diphosphate + L-tyrosinal + NADP(+) = ATP + H(+) + L-tyrosine + NADPH Secondary metabolite biosynthesis. NRP synthetases are composed of discrete domains (adenylation (A), thiolation (T) or peptidyl carrier protein (PCP) and condensation (C) domains) which when grouped together are referred to as a single module. Each module is responsible for the recognition (via the A domain) and incorporation of a single amino acid into the growing peptide product. Thus, an NRP synthetase is generally composed of one or more modules and can terminate in a thioesterase domain (TE) that releases the newly synthesized peptide from the enzyme. Occasionally, epimerase (E) domains (responsible for L- to D-amino acid conversion) are present within the NRP synthetase. LnaA contains an amino acid adenylation domain (A), a peptidyl carrier protein (PCP) domain with a phosphopantetheine prosthetic group, and a short-chain dehydrogenase/reductase terminus (R), but it does not have an identifiable condensation (C) domain required for the formation of peptide bonds during non-ribosomal peptide synthesis. Abolishes the production of piperazines and suppresses the formation of sclerotia when lnbA is also disrupted. Belongs to the NRP synthetase family.