Substrate plasticity of a fungal peptide α-N-methyltransferase

DOI: 10.1021/acschembio.0c00237

Authors: Haigang Song (Wellcome Centre for Human Genomics, University of Oxford; Research Complex at Harwell) , Jūratė Fahrig-kamarauskaitė (Eidgenössische Technische Hochschule (ETH) Zürich) , Emmanuel Matabaro (Eidgenössische Technische Hochschule (ETH) Zürich) , Hannelore Kaspar (Eidgenössische Technische Hochschule (ETH) Zürich) , Sally L. Shirran (University of St. Andrews) , Christina Zach (Eidgenössische Technische Hochschule (ETH) Zürich) , Amy Pace (Eidgenössische Technische Hochschule (ETH) Zürich) , Bozhidar-adrian Stefanov (Eidgenössische Technische Hochschule (ETH) Zürich) , James Naismith (Wellcome Centre for Human Genomics, University of Oxford; Research Complex at Harwell; Rosalind Franklin Institute) , Markus Künzler (Eidgenössische Technische Hochschule (ETH) Zürich)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Chemical Biology

State: Published (Approved)
Published: June 2020

Abstract: The methylation of amide nitrogen atoms can improve the stability, oral availability and cell permeability of peptide therapeutics. Chemical N-methylation of peptides is challenging. Omphalotin A is a ribosomally synthesized, macrocylic dodecapeptide with nine backbone N-methylations. The fungal natural product is derived from the precursor protein, OphMA, harbouring both the core peptide and a SAM-dependent peptide α-N-methyltransferase domain. OphMA forms a homodimer and its α-N-methyltransferase domain installs the methyl groups in trans on the hydrophobic core dodecapeptide and some additional C-terminal residues of the protomers. These post-translational backbone N-methylations occur in a processive manner from the N- to the C-terminus of the peptide substrate. We demonstrate that OphMA can methylate polar, aromatic and charged residues when these are introduced into the core peptide. Some of these amino acids alter the efficiency and pattern of methylation. Proline depending on its sequence context can act as a tunable stop signal. Crystal structures of OphMA variants have allowed rationalization of these observations. Our results hint at the potential to control this fungal α-N-methyltransferase for biotechnological applications.

Subject Areas: Biology and Bio-materials, Chemistry


Instruments: I03-Macromolecular Crystallography , I04-Macromolecular Crystallography