Year: 2025
Type: article
Abstract: The Escherichia coli helicase, YoaA, and DNA polymerase III subunit, χ, form a complex (YoaA-χ) that promotes tolerance to the DNA chain-terminator 3ˈ-azidothymidine (AZT). Single-stranded DNA binding protein (SSB), which accumulates at stalled replication forks, also contributes to AZT tolerance through interactions with χ. Here we show that in vitro, χ mediates interactions between YoaA and SSB that modulate helicase activity in a substrate-specific manner with little effect on overhang DNA but inhibiting unwinding of forked DNA. SSB similarly affects the activity of the YoaA paralog, DinG. Single-molecule experiments show that SSB translocates with YoaA-χ, increasing both the lifetime and frequency of SSB binding events. Mutational analyses show that χ binds at the back of YoaA relative to the direction of translocation supporting a model in which YoaA-χ pulls SSB along DNA as it translocates. To our knowledge, this is the first demonstration of a mechanoenzyme pulling SSB along ssDNA. The XPD/Rad3 helicase, YoaA-χ, helps resolve DNA damage in E. coli. Here, the authors show that single-stranded DNA binding protein (SSB) affects helicase activity in a substrate specific manner. Single molecule experiments show YoaA- χ can pull SSB along DNA while translocating
Source: Nature Communications
Authors: Savannah J. Weeks-Pollenz, Matthew J. Petrides, Kaylie A. Padgett-Pagliai, Robert Davis, Kathryn K. Harris, Linda B. Bloom
Institution: University of Florida
Language: English
Topic: DNA Repair Mechanisms
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $6,990
Awards: G111800994, G1753339502, G177653337, G2449727959, G3587218024, Mechanisms of SSB in Coordinating DNA Replication and Repair, Mechanisms and Functions of Iron-Sulfur Helicases in DNA repair, G5499864668, How SSB Regulates YoaA-chi's Function in DNA Damage Repair, G8910841240, G9000063561, G9000205887
OpenAlex ID: W4410854651