Science | A starvation survival signal fights DNA damage
The alarmone guanosine-3′,5′-(bis)pyrophosphate (ppGpp) shuts down transcription in bacteria that are starving. This “stringent response” helps them conserve energy and survive adverse conditions. Kamarthapu et al. show that ppGpp is also essential for DNA repair. ppGpp couples transcription elongation to the nucleotide excision repair pathway. ppGpp helps backtrack the RNA polymerase away from the DNA damage to facilitate repair. Through inhibiting DNA replication, it also avoids dangerous collisions between the replication fork and backtracked RNA polymerase.