High impact information on PARG

• PARG was isolated from bovine thymus, yielding a protein of approximately 59 kDa [1].
• The deduced amino acid sequence of the bovine PARG shares little or no homology with other known proteins [1].
• The transient nature of poly(ADP-ribosyl)ation, a posttranslational modification of nuclear proteins, is achieved by the enzyme poly(ADP-ribose) glycohydrolase (PARG) which hydrolyzes the poly(ADP-ribose) polymer into free ADP-ribose residues [2].
• Polyadenosine diphosphoribose glycohydrolase (PARG) catalyzes the intracellular hydrolysis of adenosine diphosphoribose polymers [3].
• A photoreactive inhibitor, [alpha-(32)P]-8-azidoadenosine diphosphate (hydroxymethyl)pyrrolidinediol (8-N(3)-ADP-HPD), was used to photolabel a recombinant bovine PARG catalytic fragment (rPARG-CF) [4].

Biological context of PARG

• PARG, despite being less abundant than PARP, is a crucial determinant of polymer metabolism which is known to be implicated in DNA repair and other cellular processes [5].

Associations of PARG with chemical compounds

• Utilizing ADP-HPD analogues containing 2-, N(6), or 8-adenosyl substituents or guanine instead of adenine, the importance of adenine ring recognition as well as a correlation between loss of PARG inhibition and the length and bulkiness of 8-adenosyl substituents was shown [3].
• N-Terminal sequencing of tryptic and subtilitic peptides of photoderivatized rPARG-CF identified tyrosine 796 (Y796), a residue conserved in PARG across a wide range of organisms, as a site of photoderivatization [4].

Analytical, diagnostic and therapeutic context of PARG

• We found that PARG purified from bovine thymus was recognized as a 59-kDa protein, while Western blot analysis of total cell extracts revealed the presence of a unique 110-kDa protein [2].
• Further analysis by immunofluorescence revealed a cytoplasmic perinuclear distribution of PARG in COS7 cells overexpressing the bovine PARG cDNA [2].
• We analysed the mode of action of PARG under conditions most suitable for expression of all the activities of PARG, using HPLC purified long free polymer and very pure PARG [6].
• Surface plasmon resonance spectroscopy using the PARG inhibitor 8-(aminohexyl)amino-ADP-HPD demonstrated that the binding constant of the inhibitor for Y796A was 21-fold lower (K(D) = 170 nM) than that of wild-type PARG (K(D) = 8.2 nM), while Y796W displayed a binding affinity similar to that of the wild-type enzyme [4].

References