Prokaryotic ubiquitin-like protein

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Prokaryotic ubiquitin-like protein (Pup) - functional analog of ubiquitin found in Prokaryote (Mycobacterium tuberculosis).[1] Serves the same function, although the enzymology of ubiquitylation and pupylation is different. In contrast to the three-step reaction of ubiquitylation, pupylation requires two steps, therefore only two enzymes are involved in pupylation. Similar to ubiquitin, Pup attaches to specific lysine residues of substrate proteins by forming isopeptide bonds, then recognized by Mycobacterium proteasomal ATPase(Mpa) by binding-induced folding mechanism[2] to form the unique alpha-helix, then Mpa deliver the Pup-substrate to 20S proteasome by coupling of ATP hydrolysis for proteasomal degradation. Therefore, like Eukaryotes, bacteria may use a small-protein modifier to control protein stability. The X-ray crystal structure of Pup/Mpa complex (PDB:3M9D)was firstly determined by scientists Tao Wang and Huilin Li in Brookhaven National Laboratory, USA.

Pup-like protein family
Pup-prokaryotic ubiquitin-like protein.png
Three Prokaryotic ubiquitin-like proteins (blue) attached to proteasomal ATPase Mpa (red)
Symbol Pup/Mpa PDB:3M9D
Pfam PF05639

Pup gene encode a 64–amino acid protein with a molecular size of 6.944-kDa:



PupDB is a database of pupylated proteins and pupylation sites[4]


  1. ^ Pearce, M. J.; Mintseris, J.; Ferreyra, J.; Gygi, S. P.; Darwin, K. H. (2008). "Ubiquitin-Like Protein Involved in the Proteasome Pathway of Mycobacterium tuberculosis". Science 322 (5904): 1104–1107. doi:10.1126/science.1163885. PMC 2698935. PMID 18832610.  edit
  2. ^ Wang T, Darwin KH, Li H. Binding-induced folding of prokaryotic ubiquitin-like protein on the Mycobacterium proteasomal ATPase targets substrates for degradation.Nat Struct Mol Biol. 2010 Nov;17(11):1352-7. doi: 10.1038/nsmb.1918.
  3. ^
  4. ^ Tung, Chun-Wei (1 January 2012). "PupDB: a database of pupylated proteins". BMC Bioinformatics 13 (1): 40. doi:10.1186/1471-2105-13-40. 

See also[edit]