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bioRxiv · 10.1101/2024.01.27.577596

Ordered and disordered regions of the Origin Recognition Complex (ORC) combine to direct in-vivo binding at symmetric and non-symmetric motif sequences.

Chappleboim, M.·Naveh-Tassa, S.·Carmi, M.·Levy, Y.·Barkai, N.
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Abstract

The Origin Recognition Complex (ORC) seeds replication-fork formation by binding to DNA replication origins, which in budding yeast contain a 17bp DNA motif. High resolution structure of the ORC-DNA complex revealed two base-interacting elements: a disordered basic patch (Orc1-BP4) and an insertion helix (Orc4-IH). To define the ORC elements guiding its DNA binding in-vivo, we mapped genomic locations of 38 designed ORC mutants, revealing that different ORC elements guide binding at different sites. At silencing-associated sites lacking the motif, ORC binding and activity were fully explained by a BAH domain. Within replication origins, we reveal two dominating motif variants showing differential binding modes and symmetry: an asymmetric motif whose binding requires Orc1-BP4 and Orc4-IH, and a symmetric one where another basic patch, Orc1-BP3, can replace Orc4-IH. Disordered basic patches are therefore key for ORC-motif binding in-vivo, and we discuss how these conserved, minor-groove interacting elements can guide specific ORC-DNA recognition.

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Chappleboim, M., Naveh-Tassa, S., Carmi, M., Levy, Y., Barkai, N.. 2024-01-30. Ordered and disordered regions of the Origin Recognition Complex (ORC) combine to direct in-vivo binding at symmetric and non-symmetric motif sequences.. https://doi.org/10.1101/2024.01.27.577596

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