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Transcript levels, alternative splicing and proteolytic cleavage of TFIIIA control 5S rRNA accumulation during Arabidopsis thaliana development
Author(s) -
Layat Elodie,
Cotterell Sylviane,
Vaillant Isabelle,
Yukawa Yasushi,
Tutois Sylvie,
Tourmente Sylvette
Publication year - 2012
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2012.04948.x
Subject(s) - ribosome biogenesis , biology , ribosomal rna , rna splicing , ribosomal protein , microbiology and biotechnology , rna , transcription (linguistics) , gene expression , alternative splicing , messenger rna , gene , ribosome , genetics , linguistics , philosophy
Summary Ribosome biogenesis is critical for eukaryotic cells and requires coordinated synthesis of the protein and rRNA moieties of the ribosome, which are therefore highly regulated. 5S ribosomal RNA, an essential component of the large ribosomal subunit, is transcribed by RNA polymerase III and specifically requires transcription factor IIIA (TFIIIA). To obtain insight into the regulation of 5S rRNA transcription, we have investigated the expression of 5S rRNA and the exon‐skipped (ES) and exon‐including (EI) TFIIIA transcripts, two transcript isoforms that result from alternative splicing of the TFIIIA gene, and TFIIIA protein amounts with respect to requirements for 5S rRNA during development. We show that 5S rRNA quantities are regulated through distinct but complementary mechanisms operating through transcriptional and post‐transcriptional control of TFIIIA transcripts as well as at the post‐translational level through proteolytic cleavage of the TFIIIA protein. During the reproductive phase, high expression of the TFIIIA gene together with low proteolytic cleavage contributes to accumulation of functional, full‐length TFIIIA protein, and results in 5S rRNA accumulation in the seed. In contrast, just after germination, the levels of TFIIIA‐encoding transcripts are low and stable. Full‐length TFIIIA protein is undetectable, and the level of 5S rRNA stored in the embryo progressively decreases. After day 4, in correlation with the reorganization of 5S rDNA chromatin to a mature state, full‐length TFIIIA protein with transcriptional activity accumulates and permits de novo transcription of 5S rRNA.