Methanobactins (Mbns) are copper-chelating natural products, first discovered in methanotrophs that utilize copper for their primary metabolic enzyme, copper-dependent particulate methane monooxygenase (pMMO).  To meet their high necessity for copper, some methanotrophs developed a specialized system where they produce Mbns to acquire copper from the environment under copper limited conditions.<br/>   Rosenzweig group has been investigating how Mbns are synthesized in methanotrophs. Mbn is ribosomally-synthesized and post-translationally modified peptide that is produced from a precursor peptide, MbnA. MbnA comprises a leader peptide that is cleaved off eventually and a core peptide that is post-translationally modified to form mature Mbn. The post-translational modifications take place at two specific cysteine residues in MbnA core peptide, resulting in the formation of the copper binding ligands, oxazolone and thioamide groups. Two core Mbn biosynthesis proteins, MbnB and MbnC, form a heterodimeric iron-containing enzyme complex, MbnBC, and catalyze the formations of the oxazolone/thioamide groups from the cysteine residues. This chemistry is believed to occur at the iron active site in MbnB in the presence of O<sub>2</sub>. In this meeting, my current efforts to investigate how to complete the Mbn biosynthesis in vitro as well as spectroscopic and kinetic analyses of MbnBC to understand its reaction mechanisms will be discussed. This work will provide insights into novel enzymatic chemistries performed by Mbn biosynthesis enzymes.

Biosynthesis of copper-chelating natural products, methanobactins

ACS Spring Meeting 2021

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