Pikromycin polyketide synthase component PikAIV (Pikromycin PKS component PikAIV) (EC 2.3.1.239) (EC 2.3.1.240) (Narbonolide/10-deoxymethynolide synthase PikA4, module 6) (Narbonolide/10-deoxymethynolide synthase PikAIV) (Type I modular polyketide synthase PikAIV) (PKS)