Transcriptionally inactive oocyte-type 5S RNA genes of Xenopus laevis are complexed with TFIIIA in vitro.

AUTOR(ES)

Peck, L J

RESUMO

An extract from whole oocytes of Xenopus laevis was shown to transcribe somatic-type 5S RNA genes approximately 100-fold more efficiently than oocyte-type 5S RNA genes. This preference was at least 10-fold greater than the preference seen upon microinjection of 5S RNA genes into oocyte nuclei or upon in vitro transcription in an oocyte nuclear extract. The approximately 100-fold transcriptional bias in favor of the somatic-type 5S RNA genes observed in vitro in the whole oocyte extract was similar to the transcriptional bias observed in developing Xenopus embryos. We also showed that in the whole oocyte extract, a promoter-binding protein required for 5S RNA gene transcription, TFIIIA, was bound both to the actively transcribed somatic-type 5S RNA gene and to the largely inactive oocyte-type 5S RNA genes. These findings suggest that the mechanism for the differential expression of 5S RNA genes during Xenopus development does not involve differential binding of TFIIIA to 5S RNA genes.

Documentos Relacionados

• Chromosomal footprinting of transcriptionally active and inactive oocyte-type 5S RNA genes of Xenopus laevis.
• Torsional stress induces an S1 nuclease-hypersensitive site within the promoter of the Xenopus laevis oocyte-type 5S RNA gene.
• Early replication and expression of oocyte-type 5S RNA genes in a Xenopus somatic cell line carrying a translocation.
• The AT-rich flanks of the oocyte-type 5S RNA gene of Xenopus laevis act as a strong local signal for histone H1-mediated chromatin reorganization in vitro.
• Both the 5S rRNA gene and the AT-rich flanks of xenopus laevis oocyte-type 5S rDNA repeat are required for histone H1-dependent repression of transcription of pol III-type genes in in vitro reconstituted chromatin.