Biosynthesis of the nosiheptide indole side ring centers on a cryptic carrier protein NosJ

• DOI: 10.1038/s41467-017-00439-1
• Publication Date: 2017-08-30T13:52:51Z
• Authors: Wei Ding; Wenjuan Ji; Yujie Wu; Runze Wu; Wan-Qiu Liu; Tianlu Mo; Junfeng Zhao; Xiaoyan Ma; Wei Zhang; Ping Xu; Zixin Deng; Boping Tang; Yi Yu; Qi Zhang
• Keywords: Indoles; Science; Q; Surface Plasmon Resonance; 01 natural sciences; Article; Streptomyces; Biosynthetic Pathways; 0104 chemical sciences; Kinetics; Thiazoles; Bacterial Proteins; Carrier Proteins; Protein Binding

AbstractNosiheptide is a prototypal thiopeptide antibiotic, containing an indole side ring in addition to its thiopeptide-characteristic macrocylic scaffold. This indole ring is derived from 3-methyl-2-indolic acid (MIA), a product of the radical S-adenosylmethionine enzyme NosL, but how MIA is incorporated into nosiheptide biosynthesis remains to be investigated. Here we report functional dissection of a series of enzymes involved in nosiheptide biosynthesis. We show NosI activates MIA and transfers it to the phosphopantetheinyl arm of a carrier protein NosJ. NosN then acts on the NosJ-bound MIA and installs a methyl group on the indole C4, and the resulting dimethylindolyl moiety is released from NosJ by a hydrolase-like enzyme NosK. Surface plasmon resonance analysis show that the molecular complex of NosJ with NosN is much more stable than those with other enzymes, revealing an elegant biosynthetic strategy in which the reaction flux is controlled by protein–protein interactions with different binding affinities.