Purification and crystallization of mono-ubiquitylated ubiquitin receptor Rpn10

Protein ubiquitylation controls nearly all cellular pathways in eukaryotes. A repertoire of proteins named ubiquitin (Ub) receptors harbouring ubiquitin-binding domains (UBDs) recognize ubiquitylated proteins. These Ub receptors decode the Ub signal by tethering a UBD or UBDs to a functional domain or domains, thus linking the ubiquitylated target to a specific function. The rapid dynamics of ubiquitylation/deubiquitylation has impeded the characterization of ubiquitylated proteins. To bypass this obstacle, a recently developed synthetic system that reconstructs the entire eukaryotic ubiquitylation cascade in Escherichia coli was used to purify the mono-ubiquitylated form of the regulatory proteasomal non-ATPase subunit (Ub-Rpn10) from Saccharomyces cerevisiae. Here, the first crystallization and data collection of Ub-Rpn10 is reported. Purified Ub-Rpn10 was crystallized in 12%(w/v) PEG 20,000, 0.1 M MES pH 6.5 and yielded thin rhombus-shaped crystals. X-ray analysis revealed that these crystals belonged to the monoclinic system C2, with unit-cell parameters a = 107.3, b = 49.7, c = 81.3 Å, α = γ = 90.0, β = 130.5°. A full synchrotron data set has been collected, merged and scaled with a diffraction limit of 3.14 Å.