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. 2021 Oct;122(10):1544-1555.
doi: 10.1002/jcb.30075. Epub 2021 Jul 5.

Universal two-point interaction of mediator KIX with 9aaTAD activation domains

Alena Hofrova  1   2 , Petr Lousa  1 , Monika Kubickova  1   3 , Jozef Hritz  1   4 , Tomas Otasevic  5 , Martin Repko  5 , Andrea Knight  6 , Martin Piskacek  6
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Universal two-point interaction of mediator KIX with 9aaTAD activation domains

Alena Hofrova et al. J Cell Biochem. 2021 Oct.

Abstract

The nine-amino-acid activation domain (9aaTAD) is defined by a short amino acid pattern including two hydrophobic regions (positions p3-4 and p6-7). The KIX domain of mediator transcription CBP interacts with the 9aaTAD domains of transcription factors MLL, E2A, NF-kB, and p53. In this study, we analyzed the 9aaTADs-KIX interactions by nuclear magnetic resonance. The positions of three KIX helixes α1-α2-α3 are influenced by sterically-associated hydrophobic I611, L628, and I660 residues that are exposed to solvent. The positions of two rigid KIX helixes α1 and α2 generate conditions for structural folding in the flexible KIX-L12-G2 regions localized between them. The three KIX I611, L628, and I660 residues interact with two 9aaTAD hydrophobic residues in positions p3 and p4 and together build a hydrophobic core of five residues (5R). Numerous residues in 9aaTAD position p3 and p4 could provide this interaction. Following binding of the 9aaTAD to KIX, the hydrophobic I611, L628, and I660 residues are no longer exposed to solvent and their position changes inside the hydrophobic core together with position of KIX α1-α2-α3 helixes. The new positions of the KIX helixes α1 and α2 allow the KIX-L12-G2 enhanced formation. The second hydrophobic region of the 9aaTAD (positions p6 and p7) provides strong binding with the KIX-L12-G2 region. Similarly, multiple residues in 9aaTAD position p6 and p7 could provide this interaction. In conclusion, both 9aaTAD regions p3, p4 and p6, p7 provide co-operative and highly universal binding to mediator KIX. The hydrophobic core 5R formation allows new positions of the rigid KIX α-helixes and enables the enhanced formation of the KIX-L12-G2 region. This contributes to free energy and is the key for the KIX-9aaTAD binding. Therefore, the 9aaTAD-KIX interactions do not operate under the rigid key-and-lock mechanism what explains the 9aaTAD natural variability.

Keywords: 9aaTAD; E2A; KIX; MLL; activation domain; p53.

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References

REFERENCES

    1. Piskacek M, Havelka M, Jendruchova K, Knight A. Nuclear hormone receptors: Ancient 9aaTAD and evolutionally gained NCoA activation pathways. J Steroid Biochem Mol Biol. 2018;187:118-123. https://doi.org/10.1016/j.jsbmb.2018.11.008
    1. Piskacek M, Havelka M, Rezacova M, Knight A. The 9aaTAD transactivation domains: from Gal4 to p53. PLOS One. 2016;11(9):e0162842.
    1. Piskacek M, Havelka M, Rezacova M, Knight A. Gal4 activation domain 9aaTAD could be inactivated by adjacent mini-inhibitory domain and reactivated by distal re-activation domain. bioRxiv. 2017:110882.
    1. Piskacek M, Jendruchova K, Rezacova M, et al. The 9aaTAD activation domains in the four Yamanaka Oct4, Sox2, Myc, and Klf4 transcription factors essential during the stem cell development. bioRxiv. 2019.
    1. Piskacek M, Vasku A, Hajek R, Knight A. Shared structural features of the 9aaTAD family in complex with CBP. Mol BioSyst. 2015;11(3):844-851.

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