Are the intrinsically disordered linkers involved in SSB binding to accessory proteins?

Min Kyung Shinn, Alexander G. Kozlov, Binh Nguyen, Wlodek M. Bujalowski, Timothy M. Lohman

    Research output: Contribution to journalArticlepeer-review

    5 Scopus citations

    Abstract

    Escherichia coli single strand (ss) DNA binding (SSB) protein protects ssDNA intermediates and recruits at least 17 SSB interacting proteins (SIPs) during genome maintenance. The SSB C-termini contain a 9 residue acidic tip and a 56 residue intrinsically disordered linker (IDL). The acidic tip interacts with SIPs; however a recent proposal suggests that the IDL may also interact with SIPs. Here we examine the binding to four SIPs (RecO, PriC, PriA and χ subunit of DNA polymerase III) of three peptides containing the acidic tip and varying amounts of the IDL. Independent of IDL length, we find no differences in peptide binding to each individual SIP indicating that binding is due solely to the acidic tip. However, the tip shows specificity, with affinity decreasing in the order: RecO > PriA ∼ χ > PriC. Yet, RecO binding to the SSB tetramer and an SSB-ssDNA complex show significant thermodynamic differences compared to the peptides alone, suggesting that RecO interacts with another region of SSB, although not the IDL. SSB containing varying IDL deletions show different binding behavior, with the larger linker deletions inhibiting RecO binding, likely due to increased competition between the acidic tip interacting with DNA binding sites within SSB.

    Original languageEnglish (US)
    Pages (from-to)8581-8594
    Number of pages14
    JournalNucleic acids research
    Volume47
    Issue number16
    DOIs
    StatePublished - Sep 19 2019

    ASJC Scopus subject areas

    • Genetics

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