Chemical synthesis of linear ADP-ribose oligomers up to pentamer and their binding to the oncogenic helicase ALC1

ADP-ribosylation is a pivotal post-translational modification that mediates various important cellular processes producing negatively charged biopolymer, poly (ADP-ribose), the functions of which need further elucidation. Toward this end, the availability of well-defined ADP-ribose (ADPr) oligomers in sufficient quantities is a necessity. In this work, we demonstrate the chemical synthesis of linear ADPr oligomers of defined, increasing length using a modified solid phase synthesis method. An advanced phosphoramidite building block temporarily protected with the base sensitive Fm-group was designed and implemented in the repeating pyrophosphate formation via a P(v)-P(iii) coupling procedure on Tentagel solid support. Linear ADPr oligomers up to a pentamer were successfully synthesized and their affinity for the poly-(ADP-ribose)-binding macrodomain of the human oncogenic helicase and chromatin remodeling enzyme ALC1 was determined. Our data reveal a length-dependent binding manner of the nucleic acid, with larger ADPr oligomers exhibiting higher binding enthalpies for ALC1, illustrating how the activity of this molecular machine is gated by PAR.Bio-organic Synthesi

The taming of PARP1 and its impact on NAD+ metabolism

Background: Poly-ADP-ribose polymerases (PARPs) are key mediators of cellular stress response. They are intimately linked to cellular metabolism through the consumption of NAD+. PARP1/ARTD1 in the nucleus is the major NAD+ consuming activity and plays a key role in maintaining genomic integrity. Scope of review: In this review, we discuss how different organelles are linked through NAD+ metabolism and how PARP1 activation in the nucleus can impact the function of distant organelles. We discuss how differentiated cells tame PARP1 function by upregulating an endogenous inhibitor, the histone variant macroH2A1.1. Major conclusions: The presence of macroH2A1.1, particularly in differentiated cells, raises the threshold for the activation of PARP1 with consequences for DNA repair, gene transcription, and NAD+ homeostasis.Research in the Ladurner and Buschbeck labs was supported by the following grants: the Deutsche Forschungsgemeinschaft SFB 646 and SFB 1064 collaborative research centers (to AGL); the Deutsche Forschungsgemeinschaft CIPSM and SyNergy research excellence clusters (to AGL); the Bavarian BioSysNet Program (to AGL); the ERA-NET Neuron project Food4Thought funded by the Bundesministerium für Bildung und Forschung (to AGL); the Marie Skłodowska Curie Training network “ChroMe” H2020-MSCA-ITN-2015-675,610 (to MB and AGL); MINECO RTI2018-094005-B-I00 (to MB); MINECO-ISCIII PIE16/00011 (to MB); the Deutsche José Carreras Leukaemie Stiftung DJCLS 14R/2018 (to MB); AGAUR 2017-SGR-305 (to MB); and Fundació La Marató de TV3 257/C/2019 (to MB). Research at the IJC is supported by the La Caixa Foundation, the Fundació Internacional Josep Carreras, Celgene Spain, and the CERCA Program/Generalitat de Catalunya

Synthesis and macrodomain binding of mono-ADP-ribosylated peptides

Mono-ADP-ribosylation is a dynamic posttranslational modification (PTM) with important roles in signaling. Mammalian proteins that recognize or hydrolyze mono-ADP-ribosylated proteins have been described. We report the synthesis of ADP-ribosylated peptides from the proteins histone H2B, RhoA and, HNP-1. An innovative procedure was applied that makes use of pre-phosphorylated amino acid building blocks. Binding assays revealed that the macrodomains of human MacroD2 and TARG1 exhibit distinct specificities for the different ADP-ribosylated peptides, thus showing that the sequence surrounding ADP-ribosylated residues affects the substrate selectivity of macrodomains.Bio-organic Synthesi

The taming of PARP1 and its impact on NAD+ metabolism

Altres ajuts: Fundació La Marató de TV3 257/C/2019 (to MB). Research at the IJC is supported by the La Caixa Foundation, the Fundació Internacional Josep Carreras, Celgene Spain.Background: Poly-ADP-ribose polymerases (PARPs) are key mediators of cellular stress response. They are intimately linked to cellular metabolism through the consumption of NAD. PARP1/ARTD1 in the nucleus is the major NAD consuming activity and plays a key role in maintaining genomic integrity. Scope of review: In this review, we discuss how different organelles are linked through NAD metabolism and how PARP1 activation in the nucleus can impact the function of distant organelles. We discuss how differentiated cells tame PARP1 function by upregulating an endogenous inhibitor, the histone variant macroH2A1.1. Major conclusions: The presence of macroH2A1.1, particularly in differentiated cells, raises the threshold for the activation of PARP1 with consequences for DNA repair, gene transcription, and NAD homeostasis

XPC-PARP complexes engage the chromatin remodeler ALC1 to catalyze global genome DNA damage repair

Cells employ global genome nucleotide excision repair (GGR) to eliminate a broad spectrum of DNA lesions, including those induced by UV light. The lesion-recognition factor XPC initiates repair of helix-destabilizing DNA lesions, but binds poorly to lesions such as CPDs that do not destabilize DNA. How difficult-to-repair lesions are detected in chromatin is unknown. Here, we identify the poly-(ADP-ribose) polymerases PARP1 and PARP2 as constitutive interactors of XPC. Their interaction results in the XPC-stimulated synthesis of poly-(ADP-ribose) (PAR) by PARP1 at UV lesions, which in turn enables the recruitment and activation of the PAR-regulated chromatin remodeler ALC1. PARP2, on the other hand, modulates the retention of ALC1 at DNA damage sites. Notably, ALC1 mediates chromatin expansion at UV-induced DNA lesions, leading to the timely clearing of CPD lesions. Thus, we reveal how chromatin containing difficult-to-repair DNA lesions is primed for repair, providing insight into mechanisms of chromatin plasticity during GGR.Cells employ global genome nucleotide excision repair to repair a broad spectrum of genomic DNA lesions. Here, the authors reveal how chromatin is primed for repair, providing insight into mechanisms of chromatin plasticity during DNA repair.Cancer Signaling networks and Molecular Therapeutic