posted on 2021-04-27, 03:29authored byXiaorui Guo, Jiabao Zhang, Xinyi Li, Emily Xiao, Justin D. Lange, Chad M. Rienstra, Martin D. Burke, Douglas A. Mitchell
Amphotericin-like
glycosylated polyene macrolides (GPMs) are a
clinically and industrially important family of natural products,
but the mechanisms by which they exert their extraordinary biological
activities have remained unclear for more than half a century. Amphotericin
B exerts fungicidal action primarily via self-assembly into an extramembranous
sponge that rapidly extracts ergosterol from fungal membranes, but
it has remained unclear whether this mechanism is applicable to other
GPMs. Using a highly conserved polyene–hemiketal region of
GPMs that we hypothesized to represent a conserved ergosterol-binding
domain, we bioinformatically mapped the entirety of the GPM sequence-function
space and expanded the number of GPM biosynthetic gene clusters (BGCs)
by 10-fold. We further leveraged bioinformatic predictions and tetrazine-based
reactivity screening targeting the electron-rich polyene region of
GPMs to discover a first-in-class methyltetraene- and diepoxide-containing
GPM, kineosporicin, and to assign BGCs to many new producers of previously
reported members. Leveraging a range of structurally diverse known
and newly discovered GPMs, we found that the sterol sponge mechanism
of fungicidal action is conserved.