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Pup-like protein This family consists of several short bacterial proteins formely known as (DUF797). It was recently shown that Mycobacterium tuberculosis contains a small protein, Pup (Rv2111c), that is covalently conjugated to the e-NH2 groups of lysines on several target proteins (pupylation) such as the malonyl CoA acyl carrier protein (FabD). Pupylation of FabD was shown to result in its recruitment to the mycobacterial proteasome and subsequent degradation analogous to eukaryotic ubiquitin-conjugated proteins. Searches recovered Pup orthologs in all major actinobacteria lineages including the basal bifidobacteria and also sporadically in certain other bacterial lineages. The Pup proteins were all between 50-90 residues in length and a multiple alignment shows that they all contain a conserved motif with a G [EQ] signature at the C-terminus. Thus, all of them are suitable for conjugation via the terminal glutamate or the deamidated glutamine (as shown in the case of the Mycobacterium). The conserved globular core of Pup is predicted to form a bihelical unit with the extreme C-terminal 6-7 residues forming a tail in the extended conformation. Thus, Pup is structurally unrelated to the ubiquitin fold and has convergently evolved the function of protein modifier. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",