The RecA-NT homology motif in ImuB mediates the interaction with ImuA', which is essential for DNA damage-induced mutagenesis.

Kęstutis Timinskas, Česlovas Venclovas, Joana A Santos, Atondaho A Ramudzuli, Meindert H Lamers, Digby F Warner, Sophia J Gessner

Journal: The Journal of biological chemistry 2025;301(2):108108

PMID: 39706264

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Abstract

The mycobacterial mutasome-comprising ImuA', ImuB, and DnaE2-has been implicated in DNA damage-induced mutagenesis in Mycobacterium tuberculosis. ImuB, which is predicted to enable mutasome function via its interaction with the β clamp, is a catalytically inactive Y-family DNA polymerase. Like some other members of the Y-family, ImuB features a recently identified amino acid motif with homology to the RecA N terminus (RecA-NT). Given the role of RecA-NT in RecA oligomerization, we hypothesized that ImuB RecA-NT mediates the interaction with ImuA', an RecA homolog of unknown function. Here, we constructed a panel of imuB alleles in which the RecA-NT was removed or mutated. Our results indicate that RecA-NT is critical for the interaction of ImuB with ImuA'. A region downstream of RecA-NT, ImuB-C, appears to stabilize the ImuB-ImuA' interaction, but its removal does not prevent complex formation. In contrast, replacing two hydrophobic residues of RecA-NT, L378 and V383, disrupts the ImuA'-ImuB interaction. To our knowledge, this is the first experimental evidence suggesting a role for RecA-NT in mediating the interaction between a Y-family member and an RecA homolog.

Address: Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands.; Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania.; SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DSI/NRF Centre of Excellence for Biomedical TB Research, Department of Pathology, University of Cape Town, Cape Town, South Africa; Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa.; SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DSI/NRF Centre of Excellence for Biomedical TB Research, Department of Pathology, University of Cape Town, Cape Town, South Africa; Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa; Wellcome Centre for Infectious Diseases Research in Africa, University of Cape Town, Cape Town, South Africa.; SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, DSI/NRF Centre of Excellence for Biomedical TB Research, Department of Pathology, University of Cape Town, Cape Town, South Africa; Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa. Electronic address: [email protected].

DOI: 10.1016/j.jbc.2024.108108

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https://antibodies.cancer.gov/detail/CPTC-NT5E-1

MeSH Terms: Rec A Recombinases, DNA Damage, Mycobacterium tuberculosis, Mutagenesis, Bacterial Proteins, Amino Acid Motifs, DNA-Directed DNA Polymerase