#Srdx domain full
#Srdx domain series

#Srdx domain full

For the full sequence alignment this panel was based on, see supplemental Fig. Conservation is high at the B3 domains but also in the region preceding B3b. B, summary of the percentage conservation within an alignment of VRN1 and its 10 most similar proteins from the GenBank TM Data Bank. The secondary structural elements are numbered for later reference. The VRN1(208–341) protein has been studied in solution by NMR, and the Cα shift data ( 6) correlated well with these predictions. Below VRN1 (from top to bottom) are the outputs from secondary structure prediction programs jalign, jfreq, jhmm, jnet, jpssm, and jpred, which suggest that only the B3 domains and a region preceding B3b are structured. Between them are two putative PEST-rich protein turnover domains and a Lys-rich nuclear localization sequence ( NLS). A, VRN1 consists of two B3 domains of ∼100 residues each. 1 A), and among the proteins most similar to VRN1, this region is the most poorly conserved in sequence ( Fig. The ∼100-residue region linking the first B3 domain to the helix before the second B3 domain is predicted to be unstructured ( Fig. A region upstream of the second B3 domain is predicted to be helical, and its Cα shifts in NMR ( 6) agreed with this prediction. VRN1 also has two putative PEST protein turnover domains and a putative nuclear localization sequence ( Fig. Furthermore, overexpression of VRN1 causes early flowering, morphological defects, and inappropriate gene expression ( 1).Īlmost two-thirds of the VRN1 protein sequence is composed of two predicted B3 DNA-binding domains, named by the discovery of the DNA binding ability of a protein region termed B3 in the maize protein VIVIPAROUS1 ( 5). For example, VRN1 is highly expressed throughout Arabidopsis and associates with transcriptionally active regions of nuclei ( 4). The reason for the failure of vrn1 mutants to vernalize is their inability during this cold treatment to suppress a key regulator of flowering, FLC ( 2, 3).Īlthough vrn1 mutants appear to have only a single phenotype, there are clues that VRN1 has much broader roles. This process is essential for many crops to flower and is a key agronomic trait. Thus, we have revealed that although VRN1 is sequence-nonspecific in DNA binding, it has a defined DNA-binding surface.Īs its name suggests, the protein VERNALIZATION1 (VRN1) was discovered for its role in Arabidopsis vernalization ( 1), a physiological process by which flowering accelerates in response to prolonged cold ( i.e. The triple mutant R249E/R289E/R296E was almost completely incapable of DNA binding in vitro.

#Srdx domain series

We established the DNA-binding face using NMR and then mutated positively charged residues on this surface with a series of 16 Ala and Glu substitutions, ensuring that the protein fold was not disturbed using heteronuclear single quantum correlation NMR spectra. The crystallized construct comprises the second VRN1 B3 domain and a preceding region conserved among VRN1 orthologs but absent in other B3 domains. To understand its sequence-nonspecific binding, we crystallized VRN1(208–341) and solved its crystal structure to 1.6 Å resolution using selenium/single-wavelength anomalous diffraction methods. In this work, we used a dominant repressor tag that overcomes genetic redundancy to show that VRN1 is involved in processes beyond vernalization that are essential for Arabidopsis development. Despite the specific phenotype of genetic vrn1 mutants, the VERNALIZATION1 (VRN1) protein localizes throughout the nucleus and shows sequence-nonspecific binding in vitro. Over 100 B3 domain-containing proteins are found in the model plant Arabidopsis thaliana, and one of these is critical for accelerating flowering in response to prolonged cold treatment, an epigenetic process called vernalization. The B3 DNA-binding domain is a plant-specific domain found throughout the plant kingdom from the alga Chlamydomonas to grasses and flowering plants.