Structural Basis of Ets1 Cooperative Binding to Widely Separated Sites on Promoter DNA

Nigar D Babayeva,Oxana I Baranovskaya,Tahir H Tahirov,Sergey Korolev

doi:10.1371/journal.pone.0033698

Nigar D Babayeva, Oxana I Baranovskaya + Show 2 more

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https://doi.org/10.1371/journal.pone.0033698

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Journal: PloS one	Publication Date: Mar 14, 2012
Citations: 19	License type: CC BY 4.0

Affiliation: University of Nebraska Medical Center

Abstract

Ets1 is a member of the Ets family of transcription factors. Ets1 is expressed in autoinhibited form and its DNA binding depends on partner proteins bound to adjacent sequences or the relative positioning of a second Ets-binding site (EBS). The autoinhibition of Ets1 is mediated by structural coupling of regions flanking the DNA-binding domain. The NMR structure of Ets1 revealed that the inhibitory regions comprised of helices HI1 and HI2 and H4 are packed together on the Ets domain to form an inhibitory module. The crystal structure of Ets1 unexpectedly revealed a homodimer in which homodimerisation occurs via swapping of HI1 helices. Modeling of DNA binding indicates that the Ets1 dimer can bind to two antiparallel pieces of DNA. To verify this, we crystallized and solved the structure of the complex comprised of Ets1 dimer and two pieces of DNA. DNA binding by Ets1 dimer resulted in formation of additional intermolecular protein•DNA interactions, implying that the complex formation is cooperative.

Highlights

Ets1, a founding member of the Ets (E-twenty-six-specific) family of transcription factors, was initially identified as the protooncogene corresponding to v-ets of the E26 leukemia virus [1,2]
The Ets proteins are often expressed in autoinhibited form and their DNA binding depends on partner proteins bound to adjacent sequences [9,10,11,12], including the relative positioning of a second Ets-binding site (EBS) [13]
Because the regions flanking the Ets domain appear to fulfill dual and opposing roles such as autoinhibition and cooperative DNA binding, we revisited the interpretation of the role of Ets1 dimer formation which we observed in crystals (Tahirov, InoueBungo and Ogata, PDB code 1gvj)

Summary

Introduction

A founding member of the Ets (E-twenty-six-specific) family of transcription factors, was initially identified as the protooncogene corresponding to v-ets of the E26 leukemia virus [1,2]. Ets autoinhibition is counteracted by direct interaction of the DNA-binding domain and/or autoinhibitory regions with regulatory partners, including Pax5 [11], Runx1 [20,21,22,23,24] and Runx2 [25,26], or by DNA-mediated homodimerization [27,28,29] In the latter case, two Ets molecules were found to bind cooperatively to the palindromic sequences in which two head-to-head EBS were separated by four base pairs [27,28,29,30,31,32,33,34]. Structural studies of two Ets bound to palindromic EBS on stromelysin-1 promoter [further referred to as (Ets1)2NDNA complex] revealed two areas of intermolecular interactions that are essential for cooperative DNA binding, and both areas contributed to the stability of the inhibitory module [36]. In all cases the end result is unmasking the DNA-binding surface of Ets

Discussion

Materials and Methods