Open Access7S-K nuclear RNA from simian virus 40-transformed cells has sequence homology to the viral early promoter.
Author(s) -
Uik Sohn,
Jolanta Szyszko,
David H. Coombs,
Margarida O. Krause
Publication year - 1983
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.80.23.7090
Subject(s) - biology , microbiology and biotechnology , rna , transcription (linguistics) , base pair , gene , nucleic acid thermodynamics , dna , enhancer , gene expression , genetics , philosophy , linguistics
Previous findings in our laboratory have identified a specific small nuclear RNA (7S-K) that promotes transcription initiation by RNA polymerase II in isolated mammalian nuclei. The present study was designed to investigate the homology between 7S-K RNAs and host and viral sequences in simian virus 40 (SV40)-transformed and in untransformed mouse 3T3 cells, with the object of testing the hypothesis that these RNAs take part in the transcription initiation complex by base pairing to promoter/enhancer regions of active genes. DNA . RNA hybridization experiments, using either Southern or RNA blotting techniques, indicated that both 7S-K and 7S-L RNAs hybridize to midrepetitive fractions of the mouse genome. However, only 7S-K RNA from transformed cells hybridized to SV40 DNA. Restriction mapping and nuclease S1 treatment of the hybridized region of SV40 yielded a 45-nucleotide-long hybrid duplex. Partial sequence analysis of the 5' end of the DNA in this duplex revealed sequence homology with the 21-base-pair repeat sequence, identified as the SV40 early promoter. Because the viral early gene is expressed in transformed cells, we conclude that 7S-K RNAs in these cells contain a species that has sequence homology to a promoter of an active gene. Taking these results together with previous ones, we postulate that the observed stimulatory activity of 7S-K RNA on transcription initiation is due to its recognition of promoter sequences, either to facilitate the formation or as part of the transcription initiation complex.