Structural highlights
Function
[TGT1_ARATH] Probable transcription factor that binds specifically to the core DNA sequence 5'-GGTTAA-3'. May act as a molecular switch in response to light signals.[1] [2] [3]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
GT-1 is a plant transcription factor that binds to one of the cis-acting elements, BoxII, which resides within the upstream promoter region of light-responsive genes. GT-1 was assumed to act as a molecular switch modulated through Ca(2+)-dependent phosphorylation/dephosphorylation in response to light signals. It was shown previously that the phosphorylation of threonine 133 in the DNA-binding domain (DBD) of GT-1 results in enhancement of the BoxII-binding activity. Interestingly, point mutation of Thr133 to Asp also enhances the BoxII-binding activity. Here, we report the solution structures of hypothetical trihelix DBDs of the wild-type (WT) and a phosphomimetic mutant (T133D) of GT-1. First, we demonstrated that the isolated DBD of GT-1 alone has the ability to bind to DNA, and that the T133D mutation of the isolated DBD can enhance the DNA-binding affinity. The structures of these DBDs turned out to be almost identical. The structural topology resembles that of Myb DBDs, but all alpha-helices are longer in GT-1. Our NMR titration experiments suggested that these longer alpha-helices yield an enlarged DNA-binding surface. The phosphorylation site is located at the N-terminus of the third alpha-helix. We built a structural model of the T133D DBD:BoxII complex with the program HADDOCK. The model resembles the structure of the TRF1 DBD:telomeric DNA complex. Interestingly, the model implies that the phosphorylated side chain may directly interact with the bases of DNA. On the basis of our findings, we propose a mechanism by which the DNA-binding activity toward BoxII of the phosphorylated GT-1 could be enhanced.
Solution structures of the trihelix DNA-binding domains of the wild-type and a phosphomimetic mutant of Arabidopsis GT-1: mechanism for an increase in DNA-binding affinity through phosphorylation.,Nagata T, Niyada E, Fujimoto N, Nagasaki Y, Noto K, Miyanoiri Y, Murata J, Hiratsuka K, Katahira M Proteins. 2010 Nov 1;78(14):3033-47. PMID:20717979[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Marechal E, Hiratsuka K, Delgado J, Nairn A, Qin J, Chait BT, Chua NH. Modulation of GT-1 DNA-binding activity by calcium-dependent phosphorylation. Plant Mol Biol. 1999 Jun;40(3):373-86. PMID:10437822
- ↑ Ayadi M, Delaporte V, Li YF, Zhou DX. Analysis of GT-3a identifies a distinct subgroup of trihelix DNA-binding transcription factors in Arabidopsis. FEBS Lett. 2004 Mar 26;562(1-3):147-54. PMID:15044016 doi:http://dx.doi.org/10.1016/S0014-5793(04)00222-4
- ↑ Hiratsuka K, Wu X, Fukuzawa H, Chua NH. Molecular dissection of GT-1 from Arabidopsis. Plant Cell. 1994 Dec;6(12):1805-13. PMID:7866025 doi:http://dx.doi.org/10.1105/tpc.6.12.1805
- ↑ Nagata T, Niyada E, Fujimoto N, Nagasaki Y, Noto K, Miyanoiri Y, Murata J, Hiratsuka K, Katahira M. Solution structures of the trihelix DNA-binding domains of the wild-type and a phosphomimetic mutant of Arabidopsis GT-1: mechanism for an increase in DNA-binding affinity through phosphorylation. Proteins. 2010 Nov 1;78(14):3033-47. PMID:20717979 doi:10.1002/prot.22827
