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 PubMed
Arabidopsis 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
- ↑ Tsukagoshi H, Saijo T, Shibata D, Morikami A, Nakamura K. Analysis of a sugar response mutant of Arabidopsis identified a novel B3 domain protein that functions as an active transcriptional repressor. Plant Physiol. 2005 Jun;138(2):675-85. Epub 2005 May 13. PMID:15894743 doi:http://dx.doi.org/pp.104.057752
- ↑ Suzuki M, Wang HH, McCarty DR. Repression of the LEAFY COTYLEDON 1/B3 regulatory network in plant embryo development by VP1/ABSCISIC ACID INSENSITIVE 3-LIKE B3 genes. Plant Physiol. 2007 Feb;143(2):902-11. doi: 10.1104/pp.106.092320. Epub 2006 Dec , 8. PMID:17158584 doi:http://dx.doi.org/10.1104/pp.106.092320
- ↑ Tsukagoshi H, Morikami A, Nakamura K. Two B3 domain transcriptional repressors prevent sugar-inducible expression of seed maturation genes in Arabidopsis seedlings. Proc Natl Acad Sci U S A. 2007 Feb 13;104(7):2543-7. doi:, 10.1073/pnas.0607940104. Epub 2007 Jan 31. PMID:17267611 doi:http://dx.doi.org/10.1073/pnas.0607940104
- ↑ Sasnauskas G, Kauneckaite K, Siksnys V. Structural basis of DNA target recognition by the B3 domain of Arabidopsis epigenome reader VAL1. Nucleic Acids Res. 2018 Apr 6. pii: 4962483. doi: 10.1093/nar/gky256. PMID:29660015 doi:http://dx.doi.org/10.1093/nar/gky256
