RNA polymerase II transcribes all mRNAs as well as several of the small nuclear RNA (snRNA) genes. Among RNA pol II genes, the U1 snRNA genes and replication dependent histone genes are distinct in their lack of intervening sequences and polyadenylated 3$\sp\prime$ ends. A unique feature of the U1 gene is that U1 3$\sp\prime$end formation requires an snRNA promoter. The promoters used in those experiments were for genes that normally form polyadenylated mRNAs. I constructed chimeric mouse histone-U1 genes to see if the U1 3$\sp\prime$end would be used when coupled to a promoter from a non-polyadenylated transcript. Using an S1 nuclease assay I showed that the transcripts do not form the U1 3$\sp\prime$end, but end at heterogeneous sites, implying that the pol II-histone transcription complex lacks a U1-specific 3$\sp\prime$end-forming activity. / It has also been reported that the transcripts initiating from U1 promoters do not direct synthesis of polyadenylated mRNA. I also constructed chimeric mouse U1-histone genes and showed that U1 promoters with at least 5 base pairs of the coding sequence highly express the histone mRNA. Transcripts of these chimeric genes mapped to the normal U1 start and formed normal histone 3$\sp\prime$ends. / When I combined these genes to make UHU genes (U1 promoter, histone coding, U1 3$\sp\prime$end), 50% of the RNAs had U1 3$\sp\prime$ends, and the other 50% were readthrough transcripts with heterogeneous ends. When I added the histone 3$\sp\prime$end to the UHU gene to make UHUH and UHHU genes, most transcripts had histone ends and were translated efficiently. Experiments comparing the stability and relative amounts of UHU and UHUH RNAs showed that a downstream histone end did not affect the efficiency of U1 3$\sp\prime$end formation, suggesting that U1 3$\sp\prime$ ends are formed by transcription termination, unlike any other pol II genes. When the distance between the U1 promoter and U1 3$\sp\prime$ end was shortened to 146, more U1 ends were formed than histone ends, demonstrating that the coupling of the U1 promoter and U1 3$\sp\prime$ end formation is distance dependent. Long UHUH transcripts with histone ends were transported to the cytoplasm and efficiently translated whereas transcripts of a similar length with U1 ends may have never left the nucleus. This suggests that the histone 3$\sp\prime$ end functions either as a signal for transport from the nucleus to the cytoplasm or as a signal for efficient translation. / Source: Dissertation Abstracts International, Volume: 51-09, Section: B, page: 4195. / Major Professor: William F. Marzluff. / Thesis (Ph.D.)--The Florida State University, 1990.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_78322 |
| Contributors | Pilch, Duane Raymond., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 183 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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