Posted by: shrikantmantri | October 10, 2009

A T9G Mutation in the Prototype TATA-box TCACTATATATAG Determines Nucleosome…

via Plant Physiology on 10/9/09

Publication Date: 2009 Oct 7 PMID: 19812181
Authors: Ranjan, A. – Ansari, S. A. – Srivastava, R. – Mantri, S. – Asif, M. H. – Sawant, S. V. – Tuli, R.
Journal: Plant Physiol

We had earlier reported that mutations to G and C at the 7(th) and 8(th) positions in the prototype TATA-box TCACTATATATAG inhibited light dependent activation of transcription from the promoter. In the present study we characterized mutations at the 9(th) position of the prototype TATA-box. Substitution of T at the 9(th) position with G or C enhanced transcription from the promoter in transgenic tobacco plants. The effect of T9G/C mutations was not light dependent though the 9G/C TATA-box showed synergy with the light responsive element (lre). However, the 9G/C mutants in the presence of lre failed to respond to phytochromes, sugar and calcium signaling in contrast to the prototype TATA-box with lre. The 9G/C mutation shifted the point of initiation of transcription and transcription activation was dependent upon the type of activating element present upstream. The synergy in activation was noticed with lre and legumin activators but not with rbcS, Pcec and PR-1a activators. The 9G mutation resulted in a micrococcal nuclease (MNase) sensitive region over TATA-box suggesting nucleosome free region in contrast to the prototype promoter which had a distinct nucleosome on the TATA-box. Thus, the transcriptional augmentation with mutation at the 9(th) position might be because of the loss of a repressive nucleosomal structure on the TATA-box. In agreement with our findings, the promoters containing TATAGATA as identified by genome wide analysis of the Arabidopsis thaliana are not tightly repressed.

post to: CiteULike


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