engleski

Macrodomain hydrolase SCO6735 from Streptomyces coelicolor reverses genotoxic stress induced by T- linked DNA ADP-ribosylation

Streptomyces species of bacteria have a very lively ADP-ribosylation metabolism. ADP- ribosylation is involved in the regulation of morphological differentiation and antibiotic production. More than 15 proteins that constitute ADP-ribosylation metabolic cycle have been found in Streptomyces coelicolor. We focused on the member of the macrodomain ADP-ribosylhydrolase SCO6735, whose disruption has been shown to increase the production of antibiotic actinorhodin. We structurally and biochemically characterized SCO6735 protein. SCO6735, shares a 19% similarity with DarG from toxin/antitoxin DarT/DarG bacterial system and 25% with human TARG1. Molecular dynamic simulations of SCO6735 WT and mutants in complex with substrate suggest a novel, substrate-assisted, catalytic mechanism. We showed that SCO6735 can reverse thymidine-linked ADP-ribosylation in vitro and in vivo. Experiments in vitro showed that SCO6735 is active on both protein and DNA modified substrates ; although it reverses DNA ADP-ribosylation on thymidines (modified by toxin DarT) much more efficiently. SCO6735 activity in vivo has been shown in heterologous (E. coli) and homologous (S. coelicolor) system. Both in vivo systems SCO6735 rescued from the toxic effect of DarT suggesting the SCO6735 might be a defence mechanism hydrolase, protecting the cell from genotoxic stress.

ADP-ribosylation ADP-ribosyl transferase ADP-ribosyl hydrolase PARP ; PARG Macrodomain Toxin-antitoxin system

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