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Category :
Languages : en
Pages :

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Author: David Jansma
Publisher: National Library of Canada = Bibliothèque nationale du Canada
ISBN: 9780612411791
Category :
Languages : en
Pages : 400

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Author: David Jansma
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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RNA polymerase (RNAP) uses ribonucleoside triphosphates as a substrate to form RNA chains. The RNA is a faithful copy of one strand of a double-stranded DNA template along which RNAP moves while making the RNA. This process (called transcription) is highly regulated such that DNA-encoded genes are transcribed at a large variety of rates and at different times in response to cues within and outside the cell. The goal of my thesis work was to investigate the mechanisms that regulate the synthesis of RNAP in yeast cells. I focused on the form of RNAP (RNAPII) of the yeast, 'Saccharomyces cerevisiae', that is responsible primarily for transcribing genes that encode proteins. I have shown that a 10-fold reduction in the level of the largest subunit of RNAPII, and likely the level of RNAPII itself, causes slow growth, temperature-sensitivity, and the inability to grow on medium lacking inositol. Hence, the level of RNAPII must be carefully maintained for normal cell growth. I next examined elements that control the synthesis of RNAPII. I have demonstrated that the DNA sequences which are upstream of the genes encoding the two largest subunits of RNAPII, namely 'RPO21' and 'RPO22', contain binding sites for two abundant transcription factors called Abf1p and Reb1p, and thymidine-rich sequences downstream of these binding sites. Both the binding sites and the T-rich regions are important for the expression of these genes. An examination of the upstream sequences of other RNAPII subunit genes revealed binding sites for Abf1p and Reb1p as well as nearby thymidine-rich sequences. This may indicate that there is a mechanism for the coordinate synthesis of RNAPII subunit genes. I sought evidence for a feedback regulatory mechanism that may control the synthesis of RNAPII. Either the underproduction of Rpo21p, or the depletion of Fcp1p, an RNAPII phosphatase that has a critical role in transcription, leads to a 5-fold increase in the expression of a reporter gene that is controlled by 'RPO21' regulatory sequences. The increase is not observed with other subunits. I discuss the implications of these results and future directions.

Author: Rodney Gerard Weilbaecher
Publisher:
ISBN:
Category :
Languages : en
Pages : 536

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Author: Susanne Jutta Hoheisel
Publisher:
ISBN:
Category :
Languages : en
Pages : 328

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Author: Ulku Uzun
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Lei Zhang
Publisher:
ISBN:
Category : Messenger RNA.
Languages : en
Pages : 288

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Author: Charles Richard Scafe
Publisher:
ISBN:
Category :
Languages : en
Pages : 238

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Author: Tracy Lanise Johnson
Publisher:
ISBN:
Category :
Languages : en
Pages : 400

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Author: Christina Chung (Ph. D.)
Publisher:
ISBN: 9781109525793
Category :
Languages : en
Pages : 53

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The nuclear Cap Binding Complex (CBC), which consists of a large subunit CBP80 and a small subunit CBP20, is structurally conserved from yeast to mammals. The complex has been implicated in multiple steps in mRNA processing including mRNA stability, pre-mRNA splicing, and mRNA export. The research described here provides evidence that the CBC plays a novel role in transcription through interactions with the RNA polymerase II (RNAPII), particularly through the C-terminal domain of the largest subunit (CTD). These interactions appear at least partially RNA independent and occur during active transcription. Although the CBC does not possess kinase or phosphatase activity, it does appear to affect CTD phosphorylation. One effect of this CBC-CTD interaction is regulation of the Nrd1 termination complex activity in attenuation of the IMP dehydrogenase gene IMD2 and its constituent cryptic unstable transcripts (CUTs). The involvement of the CBC with the RNA from capping to export and with RNAPII places it in an ideal position to provide regulatory feedback from the nascent RNA and RNA processing factors to the transcriptional machinery.