Human transcription factor TFIIIC2 specifically interacts with a unique sequence in the Xenopus laevis 5S rRNA gene.
Transcription factor TFIIIC2 derived from human cells is required for tRNA-type gene transcription and binds with high affinity to the essential B-box promoter element of tRNA-type genes. Although 5S rRNA genes contain no homology with the tRNA-type gene B box, we show that TFIIIC2 is also required for Xenopus laevis 5S rRNA gene transcription. TFIIIC2 protected an approximately 30-base-pair (-10 to +18) region of a Xenopus 5S rRNA gene from DNase I digestion. This region, which spanned the transcription start site, included sequences that are highly conserved among eucaryotic 5S rRNA genes and have no homology with the B-box sequence of tRNA genes. Mutation of the TFIIIC2-binding site reduced transcription of the 5S rRNA gene by a factor of 10 in HeLa cell extracts. Methylation of C residues within the TFIIIC2-binding site interfered with binding of TFIIIC2. These results suggest a role of the TFIIIC2-binding sequence in 5S rRNA gene transcription. In addition, the 5S rRNA gene binding site and the tRNA-type gene B-box sequence did not compete with each other for binding to TFIIIC2 any better than did an unrelated DNA sequence, indicating that TFIIIC2 interacts with 5S rRNA genes and tRNA-type genes through separate DNA-binding domains or polypeptides.
Fradkin
L G
LG
Department of Microbiology and Immunology, School of Medicine, University of California, Los Angeles 90024-1747.
Yoshinaga
S K
SK
Berk
A J
AJ
Dasgupta
A
A
D000818:Animals; D001483:Base Sequence; D001667:Binding, Competitive; D002851:Chromatography, High Pressure Liquid; D003596:Cytosine / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D006801:Humans; D008745:Methylation; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012335:RNA, Ribosomal / Q000235:genetics*; D012341:RNA, Ribosomal, 5S / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism*; D019474:Transcription Factors, TFIII; D014158:Transcription, Genetic; D014982:Xenopus laevis; D000098832:Transcription Factor TFIIIC
D012335:RNA, Ribosomal; D012341:RNA, Ribosomal, 5S; D014157:Transcription Factors; D019474:Transcription Factors, TFIII; D000098832:Transcription Factor TFIIIC; D003596:Cytosine; D004247:DNA; D003850:Deoxyribonuclease I