Document Type

Article

Language

eng

Format of Original

12 p.

Publication Date

2-2015

Publisher

Elsevier

Source Publication

Journal of Molecular Biology

Source ISSN

0022-2836

Original Item ID

DOI: 10.1016/j.jmb.2014.12.020

Abstract

The homotetrameric Escherichia coli single-stranded DNA binding protein (SSB) plays a central role in DNA replication, repair and recombination. E. coli SSB can bind to long single-stranded DNA (ssDNA) in multiple binding modes using all four subunits [(SSB)65 mode] or only two subunits [(SSB)35 binding mode], with the binding mode preference regulated by salt concentration and SSB binding density. These binding modes display very different ssDNA binding properties with the (SSB)35 mode displaying highly cooperative binding to ssDNA. SSB tetramers also bind an array of partner proteins, recruiting them to their sites of action. This is achieved through interactions with the last 9 amino acids (acidic tip) of the intrinsically disordered linkers (IDLs) within the four C-terminal tails connected to the ssDNA binding domains. Here, we show that the amino acid composition and length of the IDL affects the ssDNA binding mode preferences of SSB protein. Surprisingly, the number of IDLs and the lengths of individual IDLs together with the acidic tip contribute to highly cooperative binding in the (SSB)35 binding mode. Hydrodynamic studies and atomistic simulations suggest that the E. coli SSB IDLs show a preference for forming an ensemble of globular conformations, whereas the IDL from Plasmodium falciparum SSB forms an ensemble of more extended random coils. The more globular conformations correlate with cooperative binding.

Comments

Accepted version. Journal of Molecular Biology, Vol. 427, No. 4 (February 2015): 763-774. DOI. © Elsevier, 2015. Used with permission.

Edwin Antony was affiliated with Utah State University at the time of publication.

NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Molecular Biology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Molecular Biology. VOL 427, ISSUE 4, February 2015, DOI.

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