6fas
From Proteopedia
Crystal structure of VAL1 B3 domain in complex with cognate DNA
Structural highlights
Function[VAL1_ARATH] Transcriptional repressor of gene expression involved in embryonic pathways, such as LEC1, ABI3, and FUS3. Repressor of the sugar-inducible genes involved in the seed maturation program in seedlings. Plays an essential role in regulating the transition from seed maturation to seedling growth. Functionally redundant with VAL2/HSL1.[1] [2] [3] Publication Abstract from PubMedArabidopsis thaliana requires a prolonged period of cold exposure during winter to initiate flowering in a process termed vernalization. Exposure to cold induces epigenetic silencing of the FLOWERING LOCUS C (FLC) gene by Polycomb group (PcG) proteins. A key role in this epigenetic switch is played by transcriptional repressors VAL1 and VAL2, which specifically recognize Sph/RY DNA sequences within FLC via B3 DNA binding domains, and mediate recruitment of PcG silencing machinery. To understand the structural mechanism of site-specific DNA recognition by VAL1, we have solved the crystal structure of VAL1 B3 domain (VAL1-B3) bound to a 12 bp oligoduplex containing the canonical Sph/RY DNA sequence 5'-CATGCA-3'/5'-TGCATG-3'. We find that VAL1-B3 makes H-bonds and van der Waals contacts to DNA bases of all six positions of the canonical Sph/RY element. In agreement with the structure, in vitro DNA binding studies show that VAL1-B3 does not tolerate substitutions at any position of the 5'-TGCATG-3' sequence. The VAL1-B3-DNA structure presented here provides a structural model for understanding the specificity of plant B3 domains interacting with the Sph/RY and other DNA sequences. Structural basis of DNA target recognition by the B3 domain of Arabidopsis epigenome reader VAL1.,Sasnauskas G, Kauneckaite K, Siksnys V Nucleic Acids Res. 2018 Apr 6. pii: 4962483. doi: 10.1093/nar/gky256. PMID:29660015[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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