Fungal indole alkaloid biogenesis through evolution of a bifunctional reductase/Diels-Alderase by Dan, Q, Newmister, SA, Klas, KR, Fraley, AE, McAfoos, TJ, Somoza, AD, Sunderhaus, JD, Ye, Y, Shende, VV, Yu, F, Sanders, JN, Brown, WC, Zhao, L, Paton, RS, Houk, KN, Smith, JL, Sherman, DH, Williams, RM