Characterizing polyubiquitinated forms of the neurodegenerative ubiquitin mutant UBB +1

The ubiquitin mutant UBB +1 has been identified as a hallmark of neurodegenerative diseases. In this study, we characterize polyubiquitinated forms of UBB +1 in vitro and from patient samples. The ability of UBB +1 to be readily ubiquitinated by several E2 enzymes provided a mechanism for the controlled synthesis and purification of defined conjugates. This allowed us to utilize polyUb– UBB +1 conjugates for biochemical assays, as well as solution NMR . Coupled with our immunoassay for detection of ubiquitinated forms of UBB +1 in patient blood samples, we gain a clearer picture of the molecular mechanisms underlying neurodegenerative diseases.