Microviridins represent a ribosomally synthesized and post-translationally modified peptides (RiPPs) family that contains intramolecular ω-ester and/or ω-amide bonds between two side chains of the peptide. Most currently known microviridin-like peptides have one consensus sequence pattern and a unique ring topology. To expand the scope of the microviridin-like peptides, we determined the crosslinking connectivity of a novel modified peptide, mTgnA, and two other homologs. They contain a novel consensus sequence for the core peptide, TxxTxxxExxDxD, and the leader peptide, KPYxxxYxE, of which the core peptide forms a distinct hairpin-like bicyclic structure by the cognate ATP-grasp enzyme. In order to determine the full crosslinks connectivity of the three modified core motifs in mTgnA the ester-specific reactions and tandem mass spectrometry were used. The crosslinking reaction proceeded from the inner to outer rings, and was selective for acidic amino acids identities. We suggest that the scope of microviridin-like RiPPs is beyond the one found in microviridins and to name this expanded family of RiPPs with the microviridin-like modification as the “omega-ester containing peptides (OEPs)”.