   6.3.1.19 | ATP + [prokaryotic ubiquitin-like protein]-L-glutamate + [protein]-L-lysine = ADP + phosphate + N6-([prokaryotic ubiquitin-like protein]-gamma-L-glutamyl)-[protein]-L-lysine |
PafA catalyzes a two-step reaction by forming a gamma-glutamyl phosphate-mixed anhydride intermediate on the C-terminal glutamate of PupE by hydrolyzing ATP, followed by attaching it to nucleophilic substrates by catalyzing the formation of isopeptide bonds between PupE C-terminal glutamate gamma-carboxylate and the side chain of protein substrate lysine residues, mechanism of PafA self-pupylation, overview. K320 is the major target residue for the pupylation of PafA. During the self-pupylation of PafA, the attachment of the first Pup to PafA is catalyzed by the other PafA molecule through an intermolecular reaction, while the formation of the polymeric Pup chain is carried out in an intramolecular manner through the internal ligase activity of the already pupylated PafA. Among the three lysine residues, K7, K31 and K61, in Mycobacterium smegmatis Pup, K7 and K31 are involved in the formation of the poly-Pup chain in PafA poly-pupylation. Poly-pupylation of PafA can be reversibly regulated by depupylase Dop |
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