# Amide 1H and 15N NMR signal assignments of all naturally-occurring di-ubiquitins

## TL;DR

This paper provides NMR signal assignments for di-ubiquitins with different linkages, helping researchers study their structure and function.

## Contribution

The study reports amide 1H and 15N NMR assignments for all lysine-linked and M1-linked di-ubiquitins, revealing linkage-specific fingerprints.

## Key findings

- NMR resonance assignments show linkage-specific chemical shifts in di-ubiquitins.
- Isopeptide signals serve as fingerprints to identify linkage types via NMR spectroscopy.
- Selective isotopic labeling is emphasized for studying poly-ubiquitin chains.

## Abstract

Ubiquitin acts as a building block for a wide variety of poly-ubiquitin chains. Decoding the role of poly-ubiquitin chains in different cellular processes remains an active area of research. Here, we report amide 1H and 15N signal assignments of each ubiquitin unit in di-ubiquitins of all seven lysine linkages and in M1-linked di-ubiquitin determined by our lab over the last decade. These assignments can aid in NMR studies of the structure, dynamics, and function of various di-ubiquitins. Comparison of the NMR resonance assignments among all the di-ubiquitins revealed linkage-specific chemical shifts and isopeptide signals that can be used as “fingerprints” to directly identify using NMR spectroscopy the linkage type in a di-ubiquitin and potentially longer poly-ubiquitin chains. Our data highlight both the similarities and dissimilarities of NMR signals of ubiquitin units in di-ubiquitins of different linkages, as well as the importance of selective isotopic labeling of specific ubiquitin units in a poly-ubiquitin chain for NMR studies.