TY - JOUR
T1 - The nuclear protein IκBζ forms a transcriptionally active complex with nuclear factor-κB (NF-κB) p50 and the Lcn2 promoter via the N- and C-terminal ankyrin repeat motifs
AU - Kohda, Akira
AU - Yamazaki, Soh
AU - Sumimoto, Hideki
N1 - Funding Information:
This work was supported in part by Grant-in-Aid for Scientific Research on Innovative Areas "Oxygen Biology: a New Criterion for Integrated Understanding of Life" (no. 26111009). The authors declare that they have no conflicts of interest with the contents of this article. We thank Namiko Kubo (Kyushu University) and Yohko Kage (Kyushu University) for technical assistance, Shoko Miura (Kyushu University) for secretarial assistance, and the technical staff from the Research Support Center, Research Center for Human Disease Modeling, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
Publisher Copyright:
© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.
PY - 2016/9/23
Y1 - 2016/9/23
N2 - The nuclear protein IκBζ, comprising the N-terminal transactivation domain and the C-terminal ankyrin repeat (ANK) domain composed of seven ANK motifs, activates transcription of a subset of nuclear factor-κB (NF-κB)-dependent innate immune genes such as Lcn2 encoding the antibacterial protein lipocalin-2. Lcn2 activation requires formation of a complex containing IκBζ and NF-κB p50, a transcription factor that harbors the DNA-binding Rel homology region but lacks a transactivation domain, on the promoter with the canonical NF-κB-binding site (κB site) and its downstream cytosine-rich element. Here we show that IκBζ productively interacts with p50 via Asp-451 in the N terminus of ANK1, a residue that is evolutionarily conserved among IκBζ and the related nuclear IκB proteins Bcl-3 and IκBNS. Threonine substitution for Asp-451 abrogates direct association with the κB-site-binding protein p50, complex formation with the Lcn2 promoter DNA, and activation of Lcn2 transcription. The basic residues Lys-717 and Lys-719 in the C-terminal region of ANK7 contribute to IκBζ binding to the Lcn2 promoter, probably via interaction with the cytosine-rich element required for Lcn2 activation; glutamate substitution for both lysines results in a loss of transcriptionally active complex formation without affecting direct contact of IκBζ with p50. Both termini of the ANK domain in Bcl-3 and IκBNS function in a manner similar to that of IκBζ to interact with promoter DNA, indicating a common mechanism in which the nuclear IκBs form a regulatory complex with NF-κB and promoter DNA via the invariant aspartate in ANK1 and the conserved basic residues in ANK7.
AB - The nuclear protein IκBζ, comprising the N-terminal transactivation domain and the C-terminal ankyrin repeat (ANK) domain composed of seven ANK motifs, activates transcription of a subset of nuclear factor-κB (NF-κB)-dependent innate immune genes such as Lcn2 encoding the antibacterial protein lipocalin-2. Lcn2 activation requires formation of a complex containing IκBζ and NF-κB p50, a transcription factor that harbors the DNA-binding Rel homology region but lacks a transactivation domain, on the promoter with the canonical NF-κB-binding site (κB site) and its downstream cytosine-rich element. Here we show that IκBζ productively interacts with p50 via Asp-451 in the N terminus of ANK1, a residue that is evolutionarily conserved among IκBζ and the related nuclear IκB proteins Bcl-3 and IκBNS. Threonine substitution for Asp-451 abrogates direct association with the κB-site-binding protein p50, complex formation with the Lcn2 promoter DNA, and activation of Lcn2 transcription. The basic residues Lys-717 and Lys-719 in the C-terminal region of ANK7 contribute to IκBζ binding to the Lcn2 promoter, probably via interaction with the cytosine-rich element required for Lcn2 activation; glutamate substitution for both lysines results in a loss of transcriptionally active complex formation without affecting direct contact of IκBζ with p50. Both termini of the ANK domain in Bcl-3 and IκBNS function in a manner similar to that of IκBζ to interact with promoter DNA, indicating a common mechanism in which the nuclear IκBs form a regulatory complex with NF-κB and promoter DNA via the invariant aspartate in ANK1 and the conserved basic residues in ANK7.
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U2 - 10.1074/jbc.M116.719302
DO - 10.1074/jbc.M116.719302
M3 - Article
C2 - 27489104
AN - SCOPUS:84988637691
VL - 291
SP - 20739
EP - 20752
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 39
ER -