A kinetic model for the prevalence of mono- over poly-pupylation Academic Article uri icon


  • Bacteria belonging to the phyla Actinobacteria and Nitrospira possess proteasome cores homologous to the eukaryotic 20S proteasome particle. In these bacteria, the cytoplasmic signal for proteasomal degradation is a small protein termed Pup (prokaryotic ubiquitin-like protein). PafA, the only known Pup ligase, conjugates Pup to lysine side chains of target proteins. In contrast to the eukaryotic ubiquitin-proteasome system, where poly-ubiquitin chains are the principal tags for proteasomal degradation, mono-Pup moieties are almost exclusively observed in vivo and are sufficient as degradation tags. Although Pup presents lysines, raising the possibility of poly-Pup chain assembly, these do not predominate. At present, the factors promoting the distinct predominance of mono-over poly-pupylation remain poorly understood. To address this issue, we conducted a detailed biochemical …

publication date

  • August 16, 2015