Different sequence signatures in the upstream regions of plant and animal tRNA genes shape distinct modes of regulation.
In eukaryotes, the transcription of tRNA genes is initiated by the concerted action of transcription factors IIIC (TFIIIC) and IIIB (TFIIIB) which direct the recruitment of polymerase III. While TFIIIC recognizes highly conserved, intragenic promoter elements, TFIIIB binds to the non-coding 5'-upstream regions of the tRNA genes. Using a systematic bioinformatic analysis of 11 multicellular eukaryotic genomes we identified a highly conserved TATA motif followed by a CAA-motif in the tRNA upstream regions of all plant genomes. Strikingly, the 5'-flanking tRNA regions of the animal genomes are highly heterogeneous and lack a common conserved sequence signature. Interestingly, in the animal genomes the tRNA species that read the same codon share conserved motifs in their upstream regions. Deep-sequencing analysis of 16 human tissues revealed multiple splicing variants of two of the TFIIIB subunits, Bdp1 and Brf1, with tissue-specific expression patterns. These multiple forms most likely modulate the TFIIIB-DNA interactions and explain the lack of a uniform signature motif in the tRNA upstream regions of animal genomes. The anticodon-dependent 5'-flanking motifs provide a possible mechanism for independent regulation of the tRNA transcription in various human tissues.
Department of Biochemistry, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str 24-25, 14476 Potsdam, Potsdam, Germany.
Gong
G
Zhang
Radoslaw
R
Lukoszek
Bernd
B
Mueller-Roeber
Zoya
Z
Ignatova
D024506:5' Flanking Region; D000818:Animals; D000926:Anticodon / Q000737:chemistry; D001483:Base Sequence; D017124:Conserved Sequence; D005786:Gene Expression Regulation; D017343:Genes, Plant; D006801:Humans; D020033:Protein Isoforms / Q000378:metabolism; D012343:RNA, Transfer / Q000235:genetics*; D035361:Transcription Factor TFIIIB / Q000378:metabolism
D000926:Anticodon; D020033:Protein Isoforms; D035361:Transcription Factor TFIIIB; D012343:RNA, Transfer