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Title | Structural and mechanistic insights into the interaction of the circadian transcription factor BMAL1 with the KIX domain of the CREB-binding protein. |
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Journal, issue, pages | J Biol Chem, Vol. 294, Issue 45, Page 16604-16619, Year 2019 |
Publish date | Nov 8, 2019 |
Authors | Archit Garg / Roberto Orru / Weixiang Ye / Ute Distler / Jeremy E Chojnacki / Maja Köhn / Stefan Tenzer / Carsten Sönnichsen / Eva Wolf / |
PubMed Abstract | 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 ...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 Lys 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 Lys 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 Lys 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 Lys 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. |
External links | J Biol Chem / PubMed:31515273 / PubMed Central |
Methods | SAS (X-ray synchrotron) |
Structure data | SASDF27: SASDF37: SASDF47: SASDF57: SASDF67: SASDF77: |
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