Prokaryotic ubiquitin-like protein

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Pup-like protein family
Pup-prokaryotic ubiquitin-like protein.png
Three Prokaryotic ubiquitin-like proteins (blue) bound to proteasomal ATPase Mpa (red
Identifiers
SymbolPup
PfamPF05639
InterProIPR008515

Prokaryotic ubiquitin-like protein (Pup) is a functional analog of ubiquitin found in the prokaryote Mycobacterium tuberculosis.[1] Like ubiquitin, Pup serves to direct proteins to the proteasome for degradation in the Pup-proteasome system (PPS). However, the enzymology of ubiquitylation and pupylation is different, owing to their distinct evolutionary origins. In contrast to the three-step reaction of ubiquitylation, pupylation requires only two steps, and thus only two enzymes are involved in pupylation. The enzymes involved in pupylation are descended from glutamine synthetase.[citation needed]

Similar to ubiquitin, Pup is attached to specific lysine residues of substrate proteins by isopeptide bonds; this is called pupylation. It is then recognized by the protein Mycobacterium proteasomal ATPase (Mpa), in a mechanism that induces folding of Pup.[2] Mpa delivers the substrate protein to the proteasome for degradation by coupling of ATP hydrolysis.

The discovery of Pup indicates that like eukaryotes, bacteria may use a small-protein modifier to control protein stability.

The Pup gene encodes a 64–amino acid protein with a molecular size of about 6.9 kDa.[3]

Pup is an intrinsically disordered protein.[4] In 2010, scientists at the Brookhaven National Laboratory determined the X-ray crystal structure of the complex between Pup and its delivery enzyme Mpa 3M9D​ and found that Pup binding to Mpa induces the folding of a unique alpha-helix.[2]

In 2017, the presence of Pup homologs in bacterial species outside of the group of gram-positive bacteria was reported.[5] The Pup homologs were termed UBact (for Ubiquitin Bacterial), although the distinction has not been proven to be phylogenetically supported by a separate evolutionary origin and is without experimental evidence.[5] UBact is a homolog of Pup, and is found in several phyla of gram-negative bacteria (Pup is found predominantly in the gram-positive bacterial phylum Actinobacteria).

See also[]

References[]

  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.
  2. ^ Jump up to: a b Wang T, Darwin KH, Li H (November 2010). "Binding-induced folding of prokaryotic ubiquitin-like protein on the Mycobacterium proteasomal ATPase targets substrates for degradation". Nature Structural & Molecular Biology. 17 (11): 1352–7. doi:10.1038/nsmb.1918. PMC 2988878. PMID 20953180.
  3. ^ Universal protein resource accession number P9WHN4 for "Prokaryotic ubiquitin-like protein Pup" at UniProt.
  4. ^ Liao S, Shang Q, Zhang X, Zhang J, Xu C, Tu X (2009). "Pup, a prokaryotic ubiquitin-like protein, is an intrinsically disordered protein". 422 (2). Biochemical Journal: 207–215. doi:10.1042/BJ20090738. PMID 19580545. Cite journal requires |journal= (help)
  5. ^ Jump up to: a b Lehmann G, Udasin RG, Livneh I, Ciechanover A (February 2017). "Identification of UBact, a ubiquitin-like protein, along with other homologous components of a conjugation system and the proteasome in different gram-negative bacteria". Biochemical and Biophysical Research Communications. 483 (3): 946–950. doi:10.1016/j.bbrc.2017.01.037. PMID 28087277.

External links[]

  • PupDB, a database of pupylated proteins and pupylation sites.
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