The Zorya anti-phage defence system contains ZorAB, a membrane complex with the architecture of the flagellar stator unit. We study how Zorya detects phage infection and inactivates phage DNA.
Bacteria encode many defence systems against bacteriophages. Zorya is widespread, and three types are known. Its membrane complex ZorAB resembles the flagellar stator unit MotAB and carries a long cytoplasmic tail.
We use our knowledge of the flagellar motor to determine what activates ZorAB and how its rotation is coupled to defence.
70 nmlength of the ZorA tail
Together with the Taylor and Jackson groups, we determined cryo-EM structures of ZorAB. Five ZorA subunits surround two ZorB subunits. ZorB contains a dimeric peptidoglycan-binding domain. ZorA forms a pentameric coiled-coil tail that extends about 70 nm into the cytoplasm.
Mutational and functional analyses showed that all Zorya components are required for defence. ZorC binds DNA, and ZorD has nuclease activity. The data support a model in which ZorAB is a proton-driven motor that is activated when a phage perturbs the cell envelope. In this model, the ZorA tail recruits ZorC and ZorD, which degrade the phage DNA.
Together with the Wahl and Beisel groups, we characterised the type III-A Druantia system of Escherichia coli. DruE forms a dimer, binds exposed single-stranded DNA and unwinds DNA in the 3′-to-5′ direction. DruE and DruH together cleared phage infections without an effect on cell growth or viability.
Together with the Taylor group, we determined the cryo-EM structure of this extracellular contractile injection system. Its sheath architecture differs from that of other contractile injection systems, and a cage-like shell surrounds the central spike. Our data indicate that it interacts with the inner membrane.
DFG priority programme SPP 2330, joint project with Philipp Popp
We determine which signal activates Zorya, how its components are recruited to the infection site and how they interfere with phage DNA injection and replication. We compare Zorya types I to III in Gram-negative and Gram-positive bacteria. We use TIRF and STED microscopy, HaloTag and SNAP-tag labelling, single-molecule tracking, proximity labelling, RNA sequencing and phage screens.
Contact: Marc Erhardt, E-mail · Project page at SPP 2330
