Oligomerisation of the developmental regulator proline rich homeodomain (PRH/Hex) is mediated by a novel proline-rich dimerisation domain

Soufi, Abdenour; Smith, Corinne; Clarke, Anthony R.; Gaston, Kevin; Jayaraman, Padma-Sheela

Abstract

Homeodomain proteins regulate multiple developmental pathways by altering gene expression temporally and in a tissue-specific fashion. The Proline Rich Homeodomain protein (PRH/Hex) is a transcription factor and an essential regulator of embryonic development and haematopoiesis. Recent discoveries have implicated self-association as an important feature of transcription factor function. Here, we show using a variety of techniques including gel-filtration, analytical ultracentrifugation, electron microscopy and in vitro cross-linking, that purified recombinant PRH is oligomeric and we use in vivo cross-linking to confirm that this protein exists as oligomers in cells. This is the first demonstration that a homeodomain protein can oligomerise in vivo. Consistent with these findings we show that a fraction of endogenous and exogenous PRH appears as discrete foci within the nucleus and at the nuclear periphery. The N-terminal domain of PRH is involved in the regulation of cell proliferation and transcriptional repression and can make multiple protein–protein interactions. We show that this region of PRH contains a novel proline-rich dimerisation domain that mediates oligomerisation. We propose a model that explains how PRH forms oligomers and we discuss how these oligomers might control transcription.

• Journal Article Type: Article
• Acceptance Date: Feb 2, 2006
• Online Publication Date: Feb 28, 2006
• Publication Date: May 12, 2006
• Deposit Date: Nov 5, 2018
• Journal: Journal of Molecular Biology
• Print ISSN: 0022-2836
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 358
• Issue: 4
• Pages: 943-962
• DOI: https://doi.org/10.1016/j.jmb.2006.02.020
• Keywords: transcription; chromatin; homeodomain; oligomerisation; PRH
• Public URL: https://nottingham-repository.worktribe.com/output/1037755
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0022283606001793