Research ArticleMicrobiology

Identification of Fic-1 as an enzyme that inhibits bacterial DNA replication by AMPylating GyrB, promoting filament formation

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Science Signaling  26 Jan 2016:
Vol. 9, Issue 412, pp. ra11
DOI: 10.1126/scisignal.aad0446

AMPing down DNA replication

Bacterial Fic proteins catalyze diverse posttranslational modifications, such as AMPylation, phosphorylation, and UMPylation, and are involved in regulating bacterial filament formation. Lu et al. found that DNA yield from bacterial cultures expressing plasmids encoding Fic-1 was reduced compared to DNA yield from bacteria encoding Fic-2 or Fic-3 plasmids. This suggested that Fic-1 is involved in inhibiting DNA replication. Fic-1 AMPylated the DNA topoisomerase, needed for bacterial DNA replication, GyrB, which inhibited GyrB activity and induced SOS response. Self-AMPylation of Fic-1 inhibited its activity. The authors also identified a Fic-1 antitoxin, which they named AntF. Fic-1 expression also resulted in filament formation in bacteria through a mechanism independent of the SOS response. Thus, this study identifies one molecular target for the inhibition of DNA replication by Fic-1 and suggests that additional targets mediate the effect of Fic-1 on bacterial filament formation.

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