Dual role of phage terminase in Salmonella enterica oxidative stress response

The adaptive survival mechanisms of bacterial pathogens under host-induced stress are crucial for understanding pathogenesis.Recently,Uppalapati et al.revealed a unique dual function of the Gifsy-1 prophage terminase in Salmonella enterica:it acts as a transfer ribonuclease(tRNase)under oxidative stress.The Gifsy-1 prophage terminase targets and fragments tRNALeu to halt translation and temporarily impairs bacterial growth when exposed to high levels of ROS generated by the host immune cells.This response not only preserves genomic integrity by facilitating DNA repair but also inhibits prophage mobilization,thereby aiding in bacterial survival within vertebrate hosts.This study highlights a novel intersection between phage biology and bacterial adaptive strategies.

Architecture of the herpesvirus genomepackaging complex and implications for DNA translocation

Genome packaging is a fundamental process in a viral life cycle and a prime target of antiviral drugs.Herpesviruses use an ATP-driven packaging motor/terminase complex to translocate and cleave concatemeric dsDNA into procapsids but its molecular architecture and mechanism are unknown.We report atomic structures of a herpesvirus hexameric terminase complex in both the apo and ADP·BeF3-bound states.Each subunit of the hexameric ring comprises three components-the ATPase/terminase pUL15 and two regulator/fixer proteins,pUL28 and pUL33-unlike bacteriophage terminases.Distal to the nuclease domains,six ATPase domains form a central channel with conserved basicpatches conducive to DNA binding and trans-acting arginine fingers are essential to ATP hydrolysis and sequential DNA translocation.Rearrangement of the nuclease domains mediated by regulatory domains converts DNA translocation mode to cleavage mode.Our structures favor a sequential revolution model for DNA translocation and suggest mechanisms for concerted domain rearrangements leading to DNA cleavage.