Protein Modification by ADP-ribose via Acid-labile Linkages

Abstract

As substrate for protein-mono-ADP-ribosyltransferases, NAD has been shown to be the donor of ADP-ribose to many different nucleophiles found in proteins. This post-translational modification of proteins has been implicated in the regulation of membrane-associated processes including signal transduction, muscle cell differentiation, and protein trafficking and secretion. Described here is the preparation and chemical characterization of low molecular weight conjugates that were used as models for an acetal linkage between ADP-ribose and the hydroxyl group of a protein acceptor such as serine, threonine, tyrosine, hydroxyproline, or hydroxylysine residues. Model conjugates of ADP-ribose containing an acetal linkage were prepared, their structures were established by NMR, and the chemical stability of the linkage to ADP-ribose was studied and compared to the other known ADP-ribosyl-amino acid linkages. The rapid release of intact ADP-ribose from the acetal model conjugates in 44% formic acid distinguished them chemically from all the other known ADP-ribosyl-amino acid modifications. Rat liver proteins were shown to be modified by ADP-ribose in vivo by acid-labile linkages, providing evidence for a new class of endogenous ADP-ribose modification of animal cell proteins. The amount of modification was approximately 16 pmol of ADP-ribose per mg of total protein, and proteins modified by acid-labile linkages were detected in all subcellular fractions examined, suggesting that the scope of this modification in vivo is broad.

Beyond the Xi

“…In support of this result, this modification appears to be acidlabile (Fig. 6E) (53). This suggests that like H2A, mH2A is conjugated with ADP-ribose moieties through carboxylate ester linkages (54).…”

The intrinsic disorder alphabet. III. Dual personality of serine

“…Although arginine, cysteine, asparagine, and modified histidine (diphthamide) residues in proteins are well-established targets of the ADP-ribosylation (which is the transfer of the ADP-ribose moiety from NAD C to specific amino acid residues on substrate proteins) via the action of various protein-mono-ADP-ribosyltransferases, the capability of formation of an acetal linkage between ADP-ribose and the hydroxyl group of a protein acceptor such as serine, threonine, tyrosine, hydroxyproline, or hydroxylysine residues has been demonstrated, 253 indicating that these residues can be ADP-ribosylated. In agreement with this hypothesis, it has been established that an endoplasmic-reticulum-associated mono-ADP-ribosyltransferase PARP16/ARTD15 interacts with karyopherin-b1, and modifies neither acidic nor basic residues, but threonine or serine residues of this protein.…”

Inactivation of the Elongation Factor Tu by Mosquitocidal Toxin-Catalyzed Mono-ADP-Ribosylation

“…The instability of the ADP-ribose-amino acid bond in EF-Tu toward neutral hydroxylamine suggests the modification of arginine residues by MTX 30-264 -mediated ADP-ribosylation as well. ADP-ribose-asparagine bonds or ADP-ribose-cysteine bonds are stable toward neutral hydroxylamine, and so these amino acids can therefore be ruled out as acceptor amino acids (1,5,16). The exact arginine residue that is targeted by MTX in EF-Tu is not known yet, but possible candidates are currently under investigation.…”