Prokaryotic ubiquitin-like protein (Pup) is coupled to substrates via the side chain of its C-terminal glutamate.
A prokaryotic protein tagging system called pupylation that is analogous to ubiquitylation in eukaryotes has recently been described. In this process, prokaryotic ubiquitin-like protein (Pup) is coupled to substrate proteins via an isopeptide bond in order to target them for degradation by the proteasome. The ligation occurs via a condensation reaction involving a carboxylate of the C-terminal glutamate of Pup (located in a conserved terminal Gly-Gly-Glu motif) and the side-chain amino group of a substrate lysine. Here we have used a combination of NMR and biochemical experiments with free lysine and a physiological protein substrate (PanB) to show that the coupling occurs through the side-chain carboxylate of the glutamate in the GGE motif rather than the carboxy terminus but that the glutamate must be located at the C-terminal position to be coupled.
Sutter
Markus
M
Institute of Molecular Biology & Biophysics, ETH Zürich, CH-8093 Zürich, Switzerland.
Damberger
Fred F
FF
Imkamp
Frank
F
Allain
Frédéric H-T
FH
Weber-Ban
Eilika
E
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D018698:Glutamic Acid; D009169:Mycobacterium tuberculosis; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D014452:Ubiquitins / Q000737:chemistry* / Q000378:metabolism*
D001426:Bacterial Proteins; C533288:Pup protein, Mycobacterium tuberculosis; D014452:Ubiquitins; D018698:Glutamic Acid