Plant 7SL RNA genes belong to type 4 of RNA polymerase III- dependent genes that are composed of mixed promoters.
The genes transcribed by RNA polymerase III (pol III) display a great diversity in terms of promoter structure and are placed in four groups accordingly. Type 3 subset of pol III genes has promoter elements which reside entirely upstream of the coding region of the gene whereas type 4 consists of genes with mixed promoters that enclose intra- and extragenic regulatory sequences. Plant 7SL RNA genes have been previously classified as type 3 of pol III genes requiring an upstream sequence element and a canonical TATA box for transcriptional activity in transfected plant protoplasts. We have identified two novel functional control regions within the coding region of an Arabidopsis 7SL RNA gene (At7SL-1) that resemble tRNA gene-specific A and B boxes with respect to sequence and position. Single and multiple nucleotide substitutions in either of these regions resulted in a pronounced reduction of transcription activity in tobacco nuclear extract that was not caused by a decreased stability as shown by decay kinetics of wild type and mutant RNA transcripts. These findings suggest that plant 7SL RNA genes should be actually placed in type 4 of pol III-transcribed genes. As a consequence of substantially different upstream promoters utilized by plant and human pol III, in vitro transcription of 7SL RNA genes in heterologous systems is severely impaired. A chimeric human 7SL RNA gene that contains the 5' flanking region up to position -300 of At7SL-1 is yet transcribed with a reduced efficiency in tobacco extract when compared with the plant wild-type gene, supporting the notion that internal regulatory elements contribute to full activity.
Yukawa
Yasushi
Y
Graduate School of Natural Sciences, Nagoya City University, Nagoya 467-8501, Japan.
Felis
Martha
M
Englert
Markus
M
Stojanov
Michael
M
Matousek
Jaroslav
J
Beier
Hildburg
H
Sugiura
Masahiro
M
D017360:Arabidopsis / Q000235:genetics; D001483:Base Sequence; D005786:Gene Expression Regulation; D017343:Genes, Plant; D006801:Humans; D008969:Molecular Sequence Data; D010944:Plants / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012320:RNA Polymerase III / Q000378:metabolism*; D020733:RNA, Small Cytoplasmic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D018271:Signal Recognition Particle / Q000235:genetics*; D014026:Nicotiana; D014158:Transcription, Genetic
C115990:7SL RNA; D020733:RNA, Small Cytoplasmic; D011993:Recombinant Fusion Proteins; D018271:Signal Recognition Particle; D012320:RNA Polymerase III