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In vitro single molecule and bulk phase studies reveal the AP-1 transcription factor cFos binds to DNA without its partner cJun

Leech, James T., Brennan, Andrew, Don, Nicola A., Mason, Jody M., Kad, Neil M. (2022) In vitro single molecule and bulk phase studies reveal the AP-1 transcription factor cFos binds to DNA without its partner cJun. Journal of Biological Chemistry, 298 (8). Article Number 102229. ISSN 0021-9258. E-ISSN 1083-351X. (doi:10.1016/j.jbc.2022.102229) (KAR id:95700)

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DOI for this version: 10.22024/UniKent/01.02.95700.3271810
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Abstract

The AP-1 transcription factor family crucially regulates progression of the cell cycle, as well as playing roles in proliferation, differentiation, and the stress response. The two best described AP-1 family members, cFos and cJun, are known to dimerize to form a functional AP-1 heterodimer that binds to a consensus response element sequence. Although cJun can also homodimerize and bind to DNA, the canonical view is that cFos cannot bind DNA without heterodimerizing with cJun. Here, we show that cFos can actually bind to DNA in the absence of cJun in vitro. Using dual color single molecule imaging of cFos alone, we directly visualize binding to and movement on DNA. Of all these DNA-bound proteins, detailed analysis suggested 30-46% were homodimers. Furthermore, we constructed fluorescent protein fusions of cFos and cJun for FRET experiments. These constructs indicated complete dimerization of cJun, but although cFos could dimerize, its extent was reduced. Finally, to provide orthogonal confirmation of cFos binding to DNA we performed bulk-phase circular dichroism experiments that showed clear structural changes in DNA; these were found to be specific to the AP-1 consensus sequence. Taken together our results clearly show cFos can interact with DNA both as monomers and dimers independently of its archetypal partner, cJun.

Item Type: Article
DOI/Identification number: 10.1016/j.jbc.2022.102229
Additional information: For the purpose of open access, the author has applied a CC BY public copyright licence (where permitted by UKRI, an Open Government Licence or CC BY ND public copyright licence may be used instead) to any Author Accepted Manuscript version arising.
Uncontrolled keywords: DNA tightropes; Fluorescence; transcription factors; AP-1; CD; single-molecule
Subjects: Q Science > QH Natural history
Divisions: Divisions > Division of Natural Sciences > Biosciences
Funders: Biotechnology and Biological Sciences Research Council (https://ror.org/00cwqg982)
Depositing User: Neil Kad
Date Deposited: 07 Jul 2022 09:07 UTC
Last Modified: 25 Aug 2022 09:27 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/95700 (The current URI for this page, for reference purposes)
Kad, Neil M.: https://orcid.org/0000-0002-3491-8595
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