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Updated: Jul 28, 2025

Author Spotlight: Characterizing Novel Enzymes from Extremophiles and Common Pathogens to Understand DNA Repair and Replication
Published on: July 5, 2024
Everything OLD is new again: How structural, functional, and bioinformatic advances have redefined a neglected
Elena Wanvig Dot1, Lynn C Thomason2, Joshua S Chappie1
1Department of Molecular Medicine, Cornell University, Ithaca, New York, USA.
Abstract:
Overcoming lysogenization defect (OLD) proteins are a conserved family of ATP-powered nucleases that function in anti-phage defense. Recent bioinformatic, genetic, and crystallographic studies have yielded new insights into the structure, function, and evolution of these enzymes. Here we review these developments and propose a new classification scheme to categorize OLD homologs that relies on gene neighborhoods, biochemical properties, domain organization, and catalytic machinery. This taxonomy reveals important similarities and differences between family members and provides a blueprint to contextualize future in vivo and in vitro findings. We also detail how OLD nucleases are related to PARIS and Septu anti-phage defense systems and discuss important mechanistic questions that remain unanswered.
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