Version 2 2024-03-08, 20:11Version 2 2024-03-08, 20:11
Version 1 2024-03-07, 20:35Version 1 2024-03-07, 20:35
journal contribution
posted on 2024-03-08, 20:11authored byVasiliki
T. Chioti, Kenzie A. Clark, Jack G. Ganley, Esther J. Han, Mohammad R. Seyedsayamdost
DUF692
multinuclear iron oxygenases (MNIOs) are an emerging family
of tailoring enzymes involved in the biosynthesis of ribosomally synthesized
and post-translationally modified peptides (RiPPs). Three members,
MbnB, TglH, and ChrH, have been characterized to date and shown to
catalyze unusual and complex transformations. Using a co-occurrence-based
bioinformatic search strategy, we recently generated a sequence similarity
network of MNIO-RiPP operons that encode one or more MNIOs adjacent
to a transporter. The network revealed >1000 unique gene clusters,
evidence of an unexplored biosynthetic landscape. Herein, we assess
an MNIO-RiPP cluster from this network that is encoded in Proteobacteria
and Actinobacteria. The cluster, which we have termed mov (for methanobactin-like operon in Vibrio), encodes
a 23-residue precursor peptide, two MNIOs, a RiPP recognition element,
and a transporter. Using both in vivo and in vitro methods, we show
that one MNIO, homologous to MbnB, installs an oxazolone-thioamide
at a Thr-Cys dyad in the precursor. Subsequently, the second MNIO
catalyzes N–Cα bond cleavage of the penultimate Asn to
generate a C-terminally amidated peptide. This transformation
expands the reaction scope of the enzyme family, marks the first example
of an MNIO-catalyzed modification that does not involve Cys, and sets
the stage for future exploration of other MNIO-RiPPs.