Non-heme halogenase; part of the gene cluster that mediates the biosynthesis of radicicol, a resorcylic acid lactone (RAL) that irreversibly inhibits the HSP90 molecular chaperone, an important target for cancer chemotherapy (PubMed:18567690). The cluster encodes only two apparent post-PKS enzymes, a cytochrome P450 monooxygenase (rdc4) and a non-heme halogenase (rdc2) that could introduce the epoxide and the chlorine, respectively (PubMed:18567690). If this cluster includes all the genes required for radicicol biosynthesis, the remaining structural features of radicicol are presumably generated by the PKSs rdc1 and rdc5 (PubMed:18567690). The C-2' ketone could arise if the R-PKS rdc5 and NR-PKS rdc1 each carry out four iterations, in contrast to the five iteration-three iteration split for the hypothemycin PKSs (PubMed:18567690). The origin of the cis 5',6' double bond is not known (PubMed:18567690). The radicicol R-PKS rdc5 ER domain may catalyze either double bond isomerization or reduction in the third iteration (PubMed:18567690). Binds 1 FAD per subunit. Secondary metabolite biosynthesis. Radicicol is an important pharmacophore as an inhibitor of heat shock protein 90 (Hsp90), an ATP-dependent chaperone involved in the post-translational maturation and stabilization of over one hundred proteins, and which activity has been implicated in diverse pathologies ranging from oncology to neurodegenerative and infectious diseases (PubMed:19860733). Belongs to the flavin-dependent halogenase family.