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Bacteriophage P22 SieA mediated superinfection exclusion
Justin C Leavitt1,2, Brianna M Woodbury3,4, Eddie B Gilcrease5,6
1School of Biological Sciences, University of Utah, Salt Lake City, UT 84112 USA.
Biorxiv : the Preprint Server for Biology
|August 30, 2023
Summary
Salmonella phage P22
Area of Science:
- Bacteriophage biology
- Molecular microbiology
- Genetics
Background:
- Temperate phages utilize prophage-expressed functions to prevent superinfection.
- Salmonella phage P22 possesses four such anti-superinfection systems: c2, gtrABC, sieA, and sieB.
Approach:
- Investigated the P22-encoded SieA protein's role in superinfection exclusion.
- Identified mutations in P22 ejection proteins (genes 16 and 20) conferring resistance to SieA.
- Examined hybrid phages with HK620 ejection proteins for SieA resistance.
Key Points:
- SieA is an inner membrane protein that specifically blocks DNA injection by P22 and related phages.
- Resistance to SieA involves specific amino acid changes in the C-terminal regions of ejection proteins gp16 and gp20.
- Different SieA variants show conserved target specificity despite low sequence identity.
Conclusions:
- SieA functions as a sole protein component of the exclusion system.
- Data support a model where SieA disrupts the DNA delivery conduit formed by gp16 and gp20.
- Understanding SieA's mechanism provides insights into phage-host interactions and phage defense strategies.
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