Structural and mechanistic insights into the interaction of the circadian transcription factor BMAL1 with the KIX domain of the CREB-binding protein
The mammalian CLOCK:BMAL1 transcription factor complex and its coactivators CREB-binding protein (CBP)/p300 and mixed-lineage leukemia 1 (MLL1) critically regulate circadian transcription and chromatin modification. Circadian oscillations are regulated by interactions of BMAL1’s C-terminal transacti...
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Published in | The Journal of biological chemistry Vol. 294; no. 45; pp. 16604 - 16619 |
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Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
08.11.2019
American Society for Biochemistry and Molecular Biology |
Subjects | |
Online Access | Get full text |
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Summary: | The mammalian CLOCK:BMAL1 transcription factor complex and its coactivators CREB-binding protein (CBP)/p300 and mixed-lineage leukemia 1 (MLL1) critically regulate circadian transcription and chromatin modification. Circadian oscillations are regulated by interactions of BMAL1’s C-terminal transactivation domain (TAD) with the KIX domain of CBP/p300 (activating) and with the clock protein CRY1 (repressing) as well as by the BMAL1 G-region preceding the TAD. Circadian acetylation of Lys537 within the G-region enhances repressive BMAL1-TAD-CRY1 interactions. Here, we characterized the interaction of the CBP-KIX domain with BMAL1 proteins, including the BMAL1-TAD, parts of the G-region, and Lys537. Tethering the small compound 1–10 in the MLL-binding pocket of the CBP-KIX domain weakened BMAL1 binding, and MLL1-bound KIX did not form a ternary complex with BMAL1, indicating that the MLL-binding pocket is important for KIX-BMAL1 interactions. Small-angle X-ray scattering (SAXS) models of BMAL1 and BMAL1:KIX complexes revealed that the N-terminal BMAL1 G-region including Lys537 forms elongated extensions emerging from the bulkier BMAL1-TAD:KIX core complex. Fitting high-resolution KIX domain structures into the SAXS-derived envelopes suggested that the G-region emerges near the MLL-binding pocket, further supporting a role of this pocket in BMAL1 binding. Additionally, mutations in the second CREB-pKID/c-Myb–binding pocket of the KIX domain moderately impacted BMAL1 binding. The BMAL1(K537Q) mutation mimicking Lys537 acetylation, however, did not affect the KIX-binding affinity, in contrast to its enhancing effect on CRY1 binding. Our results significantly advance the mechanistic understanding of the protein interaction networks controlling CLOCK:BMAL1- and CBP-dependent gene regulation in the mammalian circadian clock. |
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Bibliography: | Affiliated with and financially supported by the International Ph.D. Programme on Gene Regulation, Epigenetics, and Genome Stability, Mainz, Germany. Present address: Faculty of Biology and Signalling Research Centers BIOSS and CIBSS, Albert-Ludwigs-University of Freiburg, Schänzlestr. 18, D-79104 Freiburg, Germany. Edited by Joel M. Gottesfeld |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.RA119.009845 |