An upstream U-snRNA gene-like promoter is required for transcription of theArabidopsis thaliana7SL RNA gene

Abstract

The genes transcribed by RNA polymerase (pol)111 can be placed into four distinct groups based on the nature and position of their promoter elements. In the higher eukaryotes equivalent genes usually belong to the same sub-type of pol Hi promoters and there are few examples of genes which have changed promoter type during evolution. In this work we demonstrate that the promoter of the Arabidopsis thaliana 7SL RNA gene is located upstream of the coding region and is identical to the promoters of pol III-specific plant U-small nuclear RNA (U-snRNA) genes. Sequence analysis of two different 7SL genes from A.thaliana revealed that both genes contain two sequence elements in their 5' flanking regions identical in sequence and position to the highly conserved USE and TATA elements of the pol III-transcribed plant U-snRNA genes. Mutational analysis of these elements in the At7SL-2 gene indicates that the USE and TATA elements are both necessary and account for >90°% of the transcriptional activity of this gene in transfected plant protoplasts. Within the coding region of both genes there is a sequence element which is a 10/11 nt match to the consensus B-box element of tRNA genes, however, this element is not important for gene activity. These findings distinguish the plant genes from the human 7SL gene, which has both intemal and upstream promoter elements and its upstream elements are different from those found in the human U-snRNA genes.

Intragenic Promoter Adaptation and Facilitated RNA Polymerase III Recycling in the Transcription of SCR1, the 7SL RNA Gene ofSaccharomyces cerevisiae

“…In humans, 7SL RNA gene transcription requires both an extended upstream region (7), including a binding site for the RNA polymerase II activator ATF (8), and an unusual intragenic promoter element that stimulates transcription through a structural motif at the 5Ј end of the nascent transcript (9 -11). At variance with the human genes, plant 7SL gene transcription only requires an upstream promoter composed of a TATA box and an upstream stimulatory element identical to that of all plant U-snRNA gene promoters (12). Yet another promoter organization is found in the 7SL genes of protozoans of the family Trypanosomatidae, whose transcription depends on the A-and B-blocks of a divergently oriented, companion tRNA gene positioned 100 bp upstream of the 7SL transcription start site (13,14).…”

Molecular analysis of the gene family of the signal recognition particle (SRP) RNA of tomato

“…Mutational analysis in the human system has revealed that a CG dinucleotide at position + 15/+ 16 is absolutely required for expression [3] and that a binding site for the transcriptional activator ATF located around -50 may be involved in the pol III-specific expression [4]. In contrast to that, mutational analysis of the promoter organization in A rabidopsis thaliana [ 22 ] indicated that in this dicotyledonous plant the 7SL genes belong to another pol III subclass that include genes with promoter elements found exclusively upstream of the coding region.…”

“…Additional dicot SRP RNA sequences were studied in Arabidopsis thaliana [22,29,46]. All these studies showed that, in contrast to non-plant species, in higher plants a heterogeneous sequence population of the SRP RNA is present.…”

“…In contrast to the wealth of information concerning SRP RNA sequences (reviewed in 28), only limited data are available on the organization of the eukaryotic SRP RNA genes derived from Schizosaccharomyces pombe [5,41 ], Yarrowia lipolytica [19,20,38], Saccharomyces cerevisiae [14], Tetrahymena thermophila [6], Trypanosoma brucei [33], human cells [50] and Arabidopsis thaliana [22,46]. To our knowledge, so far, no conservation of the promoter structure has been found between the eukaryotic SRP RNA gene homologues although it is assumed that all eukaryotic SRP RNA genes are transcribed by DNA-dependent RNA polymerase III (pol III).…”

“…To our knowledge, so far, no conservation of the promoter structure has been found between the eukaryotic SRP RNA gene homologues although it is assumed that all eukaryotic SRP RNA genes are transcribed by DNA-dependent RNA polymerase III (pol III). Information about the regulation of SRP RNA genes was restricted to studies of the human SRP RNA gene family but most recently the possible regulation of two SRP RNA genes from Arab# dopsis thaliana [22] has been investigated. In the human genome ca.…”