The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions

The transcription factor Pax6 is essential for the development of the eyes and the central nervous system of vertebrates and invertebrates. Pax6 contains two DNA-binding domains; an N-terminal paired domain and a centrally located homeodomain. We have previously shown that the vertebrate paired-less...

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Main Authors:	Bruun, Jack-Ansgar, Thomassen, Ernst Ivan Simon, Kristiansen, Kurt, Tylden, Garth, Holm, Turid, Mikkola, Ingvild, Bjørkøy, Geir, Johansen, Terje
Format:	Online
Language:	English
Published:	Oxford University Press 2005
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1092277/

id	pubmed-1092277
recordtype	oai_dc
spelling	pubmed-10922772005-05-11 The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions Bruun, Jack-Ansgar Thomassen, Ernst Ivan Simon Kristiansen, Kurt Tylden, Garth Holm, Turid Mikkola, Ingvild Bjørkøy, Geir Johansen, Terje Article The transcription factor Pax6 is essential for the development of the eyes and the central nervous system of vertebrates and invertebrates. Pax6 contains two DNA-binding domains; an N-terminal paired domain and a centrally located homeodomain. We have previously shown that the vertebrate paired-less isoform of Pax6 (Pax6ΔPD), and several other homeodomain proteins, interact with the full-length isoform of Pax6 enhancing Pax6-mediated transactivation from paired domain-DNA binding sites. By mutation analyses and molecular modeling we now demonstrate that, surprisingly, the recognition helix for specific DNA binding of the homeodomains of Pax6 and Chx10 interacts with the C-terminal RED subdomain of the paired domain of Pax6. Basic residues in the recognition helix and the N-terminal arm of the homeodomain form an interaction surface that binds to an acidic patch involving residues in helices 1 and 2 of the RED subdomain. We used fluorescence resonance energy transfer assays to demonstrate such interactions between Pax6 molecules in the nuclei of living cells. Interestingly, two mutations in the homeodomain recognition helix, R57A and R58A, reduced protein–protein interactions, but not DNA binding of Pax6ΔPD. These findings suggest a critical role for the recognition helix and N-terminal arm of the paired class homeodomain in protein–protein interactions. Oxford University Press 2005 2005-05-10 /pmc/articles/PMC1092277/ /pubmed/15886395 http://dx.doi.org/10.1093/nar/gki562 Text en © The Author 2005. Published by Oxford University Press. All rights reserved
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Bruun, Jack-Ansgar Thomassen, Ernst Ivan Simon Kristiansen, Kurt Tylden, Garth Holm, Turid Mikkola, Ingvild Bjørkøy, Geir Johansen, Terje
spellingShingle	Bruun, Jack-Ansgar Thomassen, Ernst Ivan Simon Kristiansen, Kurt Tylden, Garth Holm, Turid Mikkola, Ingvild Bjørkøy, Geir Johansen, Terje The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions
author_facet	Bruun, Jack-Ansgar Thomassen, Ernst Ivan Simon Kristiansen, Kurt Tylden, Garth Holm, Turid Mikkola, Ingvild Bjørkøy, Geir Johansen, Terje
author_sort	Bruun, Jack-Ansgar
title	The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions
title_short	The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions
title_full	The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions
title_fullStr	The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions
title_full_unstemmed	The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions
title_sort	third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for dna and protein interactions
description	The transcription factor Pax6 is essential for the development of the eyes and the central nervous system of vertebrates and invertebrates. Pax6 contains two DNA-binding domains; an N-terminal paired domain and a centrally located homeodomain. We have previously shown that the vertebrate paired-less isoform of Pax6 (Pax6ΔPD), and several other homeodomain proteins, interact with the full-length isoform of Pax6 enhancing Pax6-mediated transactivation from paired domain-DNA binding sites. By mutation analyses and molecular modeling we now demonstrate that, surprisingly, the recognition helix for specific DNA binding of the homeodomains of Pax6 and Chx10 interacts with the C-terminal RED subdomain of the paired domain of Pax6. Basic residues in the recognition helix and the N-terminal arm of the homeodomain form an interaction surface that binds to an acidic patch involving residues in helices 1 and 2 of the RED subdomain. We used fluorescence resonance energy transfer assays to demonstrate such interactions between Pax6 molecules in the nuclei of living cells. Interestingly, two mutations in the homeodomain recognition helix, R57A and R58A, reduced protein–protein interactions, but not DNA binding of Pax6ΔPD. These findings suggest a critical role for the recognition helix and N-terminal arm of the paired class homeodomain in protein–protein interactions.
publisher	Oxford University Press
publishDate	2005
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1092277/
_version_	1611374387854835712

The third helix of the homeodomain of paired class homeodomain proteins acts as a recognition helix both for DNA and protein interactions

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