[Primary structure of the 5S rRNA gene with shortened non-transcribed spacer in diploid wheat Triticum monococcum L]

Abstract

Two types of repeated sequences 320 and 510 b. p. long, that hybridize with 32P-5S rRNA, were determined in the genome of diploid wheat Triticum monococcum L. Using pBR327 plasmid, recombinant plasmids pTm5S7 and pTmS12, containing 5S DNA of both types, were constructed. The primary structure of the insertion into plasmid pTm5S7 was determined. The given 5S DNA repeated unit was shown to consist of 327 base pairs and to lack highly diverged sequence between 133 and 214 bases in 3'-flanking region. Eight nucleotide changes in the encoding region, including four changes in the transcription control region were found. Partial or full elimination of 5S DNA repeats were shown in genomes of tetra- and hexaploid wheat species. It was supposed that 5S DNA gene of Triticum monococcum in 327 b. p. repeats should represent a gene with relatively low transcriptional activity due to base changes within the limits of the intragene transcription control region.