title: Chloride binding by the AML1/Runx1 transcription factor studied by NMR.
abstract: It is known that the DNA binding Runt domain of the AML1/Runx1 transcription factor coordinates Cl(-) ions. In this paper we have determined Cl(-) binding affinities of AML1 by (35)Cl nuclear magnetic resonance (NMR) linewidth analysis. The Runt domain binds Cl(-) with a dissociation constant (K(d,Cl)) of 34 mM. If CBFbeta is added to form a 1:1 complex, the K(d,Cl) value increases to 56 mM. Homology modeling suggests that a high occupancy Cl(-) binding site overlaps with the DNA binding surface. NMR data show that DNA displaces this Cl(-) ion. Possible biological roles of Cl(-) binding are discussed based on these findings.
authors.affiliation: Department of Biotechnology, Royal Institute of Technology, Center for Structural Biochemistry, Novum, Huddinge, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Wolf-Watz
authors.forename: S
authors.initials: S
authors.lastname: Bäckström
authors.forename: T
authors.initials: T
authors.lastname: Grundström
authors.forename: U
authors.initials: U
authors.lastname: Sauer
authors.forename: T
authors.initials: T
authors.lastname: Härd
mesh_terms: D000595:Amino Acid Sequence; D001667:Binding, Competitive; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D050676:Core Binding Factor Alpha 2 Subunit; D004247:DNA / Q000037:antagonists & inhibitors / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins; D016415:Sequence Alignment; D013816:Thermodynamics; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D002712:Chlorides; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D004247:DNA