Atrochrysone carboxyl ACP thioesterase; part of the gene cluster that mediates the biosynthesis of endocrocin, a simple anthraquinone interesting for many biotechnological applications (PubMed:22492455, PubMed:23592999). The pathway begins with the synthesis of atrochrysone thioester by the polyketide synthase (PKS) encA (PubMed:22492455). The atrochrysone carboxyl ACP thioesterase encB then breaks the thioester bond and releases the atrochrysone carboxylic acid from encA (PubMed:22492455). The atrochrysone carboxylic acid is then converted to endocrocin anthrone which is further oxidized into endocrocin by the anthrone oxygenase encC (PubMed:22492455). The exact function of encD has not been identified yet, but it negatively regulates endocrocin production, likely through the modification of endocrocin itself (PubMed:22492455). atrochrysone carboxyl-[ACP] + H2O = atrochrysone carboxylate + H(+) + holo-[ACP] Binds 2 Zn(2+) ions per subunit. Endocrocin is specifically produced in conidia. Expression is positively regulated by the transcription factors brlA and laeA (PubMed:26242966). Abolishes the production of endocrocin (PubMed:22492455). Endocrocin and related anthraquinones compounds have interesting activities for medicinal uses, including anti-inflammatory activity (PubMed:20379952). Belongs to the metallo-beta-lactamase superfamily.