Hybrid PKS-NRPS synthetase; part of the gene cluster that mediates the biosynthesis of the toxin tenuazonic acid (TeA), an inhibitor of protein biosynthesis on ribosomes by suppressing the release of new protein (PubMed:26503170, PubMed:28820236, PubMed:32765467, PubMed:32565425). TAS1 alone is sufficient for TeA synthesis via the condensation of isoleucine (Ile) with acetoacetyl-CoA by the N-termainal NRPS module and subsequent cyclization conducted by the C-terminal KS domain (PubMed:26503170, PubMed:32565425). acetoacetyl-CoA + ATP + L-isoleucine = AMP + CoA + diphosphate + 2 H(+) + tenuazonic acid Expression is induced by the presence of dimethylsulphoxide (DMSO) or by the deletion of OSM1, a HOG1-related mitogen-activated protein kinase (PubMed:26503170). Expression is directly induced by the TeA-specific transcription factor TAS2 which is itself regulated by the secondary metabolism regulator LAE1 (PubMed:28820236). Infection by the totivirus activates the expression of TAS1 by up-regulating the transcription of the gene transcription factor TAS2 (PubMed:32765467). The PKS portion of TAS1 has only a ketosynthase (KS) domain and this domain is indispensable for TAS1 activity by conducting the final cyclization step for tenuazonic acid release (PubMed:26503170, PubMed:32565425). The KS domain has intrinsic tolerance for a broad range of substrates since it is able to accept also TeA analogs containing leucine (Leu), phenylalanine (Phe) and valine (Val) instead of isoleucine (Ile) (PubMed:32565425). Impairs the production of tenuazonic acid (PubMed:26503170). In the N-terminal section; belongs to the NRP synthetase family.