title: The C-terminal domain of Eos forms a high order complex in solution.
abstract: Ikaros family transcription factors play important roles in the control of hematopoiesis. Family members are predicted to contain up to six classic zinc fingers that are arranged into N- and C-terminal domains. The N-terminal domain is responsible for site-specific DNA binding, whereas the C-terminal domain primarily mediates the homo- and hetero-oligomerization between family members. Although the mechanisms of action of these proteins are not completely understood, the zinc finger domains are known to play a central role. In the current study, we have sought to understand the physical and functional properties of these domains, in particular the C-terminal domain. We show that the N-terminal domain from Eos, and not its C-terminal region, is required to recognize GGGA consensus sequences. Surprisingly, in contrast to the behavior exhibited by Ikaros, the C-terminal domain of Eos inhibits the DNA-binding activity of the full-length protein. In addition, we have used a range of biophysical techniques to demonstrate that the C-terminal domain of Eos mediates the formation of complexes that consist of nine or ten molecules. These results constitute the first direct demonstration that Ikaros family proteins can form higher order complexes in solution, and we discuss this unexpected result in the context of what is currently known about the family members and their possible mechanism of action.
authors.affiliation: School of Molecular and Microbial Biosciences, University of Sydney, New South Wales 2006, Australia.
authors.forename: Belinda J
authors.initials: BJ
authors.lastname: Westman
authors.forename: José
authors.initials: J
authors.lastname: Perdomo
authors.forename: Margaret
authors.initials: M
authors.lastname: Sunde
authors.forename: Merlin
authors.initials: M
authors.lastname: Crossley
authors.forename: Joel P
authors.initials: JP
authors.lastname: Mackay
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism* / Q000502:physiology; D016384:Consensus Sequence; D004268:DNA-Binding Proteins; D019281:Dimerization; D051740:Ikaros Transcription Factor; D009419:Nerve Tissue Proteins / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000502:physiology; D016415:Sequence Alignment; D012996:Solutions; D014157:Transcription Factors; D016335:Zinc Fingers / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; D012996:Solutions; D014157:Transcription Factors; C118760:Zfpn1a4 protein, mouse; D051740:Ikaros Transcription Factor