An intrinsically bent region upstream of the transcription start site of the rRNA genes of Arabidopsis thaliana interacts with an HMG-related protein

Abstract

Intrinsically bent DNA structures are thought to play crucial roles as functionally important modules in promoter/enhancer elements. Here we show the existence of a DNA bending centre within the intergenic region of the tandemly arranged rRNA genes of Arabidopsis thaliana. By use of a circular permutation assay, this bending centre was localized to position -284 to -256 upstream of the transcription start site. A 143 bp fragment containing the bent region was shown to interact with several nuclear proteins. Evidence is presented that one of these proteins is related to the high-mobility-group (HMG) proteins, a group thought to be involved in transcription and replication processes.

Tobacco ribosomal DNA spacer element stimulates amplification and expression of heterologous genes

“…Transcription activation by aps is not particularly surprising, in that it is located upstream of the transcription initiation site in tobacco rDNA IGS. In several plant species this region of IGS has been shown to contain an intrinsic DNA bending center, which is implicated in the regulation and/or initiation of transcription, replication, and recombination by facilitating specific protein-DNA interactions 30 . Bent DNA regions are characterized by the A+T-rich sequences such as putative bent DNA motives 31 , and/or scaffold-attached regions (SAR) 32 , which are present in multiple copies in the aps.…”

Ribosomal transcription units integrated via T‐DNA transformation associate with the nucleolus and do not require upstream repeat sequences for activity in Arabidopsis thaliana

“…The system should also complement a number of efforts to define parts of the intergenic region important for rRNA synthesis which have so far relied on gel mobility shift assays to detect DNA-protein interactions (Ashapkin et al, 1995;Echeverria et aL, 1992;Echeverria et aL, 1994;Griess et aL, 1993;Kneidl et aL, 1995;Nakajima et al, 1992;Zentgraf and Hemleben, 1992). Previously, comparative analysis of rDNA intergenic regions has lead to models (Cordesse etal., 1993;Gr0ndler etal., 1991;Hemleben and Zentgraf, 1994;King et aL, 1993) which can now be tested for the model plant species A. thaliana.…”

Two Ribosomal DNA‐Binding Factors Interact with a Cluster of Motifs on the 5′ External Transcribed Spacer, Upstream from the Primary Pre‐rRNA Processing Site in a Higher Plant

“…In this latter example, described in Cucumis melo, these 5' ETSbinding factors are low-molecular-mass proteins that interact with (dA+dT)-rich sequences and bind to single-stranded DNA Hemleben, 1992, 1993). The role of these factors remains unknown but some may be related to high-mobilitygroup proteins (Kneidl et al, 1995). In constrast to these plant rDNA-binding activities, NF D has a very high specificity for a unique double-stranded DNA sequence on the IGS, the AT2' cluster of three 10-bp motifs, located downstream from the TIS.…”