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Updated: Jun 16, 2026

Characterization of a Pathogenic Escherichia coli Strain Derived from Oreochromis spp. Farms Using Whole-Genome Sequencing
Published on: December 23, 2022
The uncharacterized E. coli gene ybjD encodes a novel Class 1 OLD protein
Leslie T Atahualpa1, Jordan L Polster1, Jennifer Monzon1
1Biology Department, Davidson College, Davidson, NC 28035, USA.
Abstract:
Overcoming Lysogenization Defect (OLD) proteins demonstrate anti-phage defense in multi-gene systems including the Gabija system and some retrons, but isolated OLD genes remain poorly understood. Here we show the uncharacterized E. coli gene ybjD encodes an OLD protein producing anti-phage phenotypes upon induced expression. The Toprim domain is dispensable while the ATPase domain is essential for these phenotypes. Unexpectedly, a Walker A mutant predicted to prevent ATP binding retains anti-phage phenotypes but exhibits enhanced cytotoxicity. Together, these findings suggest ATP binding modulates YbjD activity. We propose renaming ybjD as oldB , a Class 1 OLD protein in E. coli .
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