Systematic analysis of ADP-ribose detection reagents and optimisation of sample preparation to detect ADP-ribosylation in vitro and in cells

Recent evidence suggests that modification of substrates with a single ADP-ribose (ADPr) is important in for example antiviral immunity and cancer. However, the endogenous substrates and the extent of mono-ADP-ribosylation are still largely unclear. Several reagents were developed to detect ADP-ribosylation but it is unknown whether they recognise only ADPr, amino acid-ADPr linkages or a combination of ADPr with a protein backbone. We screened the affinity of selected reagents for enzymatically, chemically and in cell generated ADP-ribosylation on glutamate, cysteine, serine, arginine, threonine and RNA by blotting, as well as analysed the subcellular sites of ADP-ribosylation using immunofluorescence confocal microscopy. We furthermore observed that the modification is heat-labile and optimised sample preparation procedures. Our comparison of the available reagents, as well as optimisation of sample preparation, will allow future work further dissecting the function of ADP-ribosylation in cells, both on protein and on RNA substrates.