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Rapid Analysis of ADP-Ribosylation Dynamics and Site-Specificity Using TLC-MALDI
Sean R Wallace1, Leila Y Chihab1, Miles Yamasaki1
1Santa Clara University, Department of Chemistry and Biochemistry, Santa Clara, California 95053, United States.
Abstract:
Poly(ADP-ribose) polymerases, PARPs, transfer ADP-ribose onto target proteins from nicotinamide adenine dinucleotide (NAD+). Current mass spectrometric analytical methods require proteolysis of target proteins, limiting the study of dynamic ADP-ribosylation on contiguous proteins. Herein, we present a matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) method that facilitates multisite analysis of ADP-ribosylation. We observe divergent ADP-ribosylation dynamics for the catalytic domains of PARPs 14 and 15, with PARP15 modifying more sites on itself (+3-4 ADP-ribose) than the closely related PARP14 protein (+1-2 ADP-ribose)─despite similar numbers of potential modification sites. We identify, for the first time, a minimal peptide fragment (18 amino-acids) that is preferentially modified by PARP14. Finally, we demonstrate through mutagenesis and chemical treatment with hydroxylamine that PARPs 14/15 prefer acidic residues. Our results highlight the utility of MALDI-TOF in the analysis of PARP target modifications and in elucidating the biochemical mechanism governing PARP target selection.
Insights
This study introduces a new MALDI-TOF method for analyzing Poly(ADP-ribose) polymerases (PARPs) modifications. The method reveals PARP15 modifies more sites than PARP14, and both PARPs favor acidic residues.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteomics
Background:
- Poly(ADP-ribose) polymerases (PARPs) are crucial enzymes involved in DNA repair and other cellular processes.
- ADP-ribosylation, the post-translational modification catalyzed by PARPs, plays a vital role in regulating protein function.
- Existing mass spectrometry methods for analyzing ADP-ribosylation require protein digestion, hindering the study of dynamic modifications on intact proteins.
Purpose of the Study:
- To develop a novel matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) method for analyzing multisite ADP-ribosylation.
- To investigate and compare the ADP-ribosylation dynamics of PARP14 and PARP15 catalytic domains.
- To identify specific peptide targets and preferred residues for PARP-mediated ADP-ribosylation.
Main Methods:
- Development and application of a MALDI-TOF-based assay for ADP-ribosylation analysis.
- Comparative analysis of ADP-ribosylation patterns on PARP14 and PARP15 catalytic domains.
- Mutagenesis studies and chemical treatments (hydroxylamine) to probe residue preference.
Main Results:
- The developed MALDI-TOF method enables efficient multisite ADP-ribosylation analysis without protein digestion.
- PARP15 exhibits higher modification activity, adding more ADP-ribose units (+3-4) to itself compared to PARP14 (+1-2).
- A minimal 18-amino acid peptide fragment was identified as a preferential target for PARP14, and acidic residues were confirmed as preferred modification sites for both PARPs.
Conclusions:
- MALDI-TOF is a valuable tool for studying dynamic PARP-mediated protein modifications.
- PARP14 and PARP15 display distinct ADP-ribosylation activities and target specificities.
- Understanding PARP target selection mechanisms, particularly the preference for acidic residues, provides insights into their biological functions.
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