Archaea are characterized by a unique life style in often environmental extremes but their thorough investigation is currently hampered by a limited set of suitable in vivo research methodologies. Here, we demonstrate that in vivo activity-based protein profiling (ABPP) may be used to sensitively detect either native or heterogeneously expressed active enzymes in living archaea even under these extreme conditions. In combination with the development of a genetically engineered archaeal screening strain, ABPP can furthermore be used in functional enzyme screenings from (meta)genome samples. We anticipate that our ABPP approach may therefore find application in basic archaeal research but also in the discovery of novel enzymes from (meta)genome libraries.

Polyacetylenes are a class of alkyne-containing natural products. Although potent bioactivities and thus possible applications as chemical probes have already been reported for some polyacetylenes, insights into the biological activities or molecular mode of action are still rather limited in most cases. To overcome this limitation, we describe the application of the polyacetylene callyspongynic acid in the development of an experimental roadmap for characterizing potential protein targets of alkyne-containing natural products. To this end, we undertook the first chemical synthesis of callyspongynic acid. We then used in situ chemical proteomics methods to demonstrate extensive callyspongynic acid-mediated chemical tagging of endoplasmic reticulum-associated lipid-metabolizing and modifying enzymes. We anticipate that an elucidation of protein targets of natural products may serve as an effective guide to the development of subsequent biological assays that aim to identify chemical phenotypes and bioactivities.

Natural products (NPs) are an important inspirational source for developing drugs and chemical probes. In 1999, the group of Ō mura reportedt he constitutional elucidation of zelkovamycin. Although largely unrecognized so far,t his NP displays structural similarities as well as differences to the argyrin NP family, ac lass of peptidic NPs with promising anticancer activities and diverse mode-of-action at the molecular level. By ac ombination of structure elucidation experiments, the first total synthesis of zelkovamycin and bioassays, the zelkovamycin configuration was determined and its previously proposed molecular structure was revised. The full structure assignment provesz elkovamycin as an additional member of the argyrins with however unique OXPHOSi nhibitory properties. Zelkovamycin may therefore not only serve as an ew startingp oint for chemical inhibitors of the OXPHOSs ystem,b ut also guide customized argyrin NP isolationa nd biosynthesis studies.