Cys2-His2 zinc-finger transcription factors in the regulation of expression of the 5S RNA and DIT genes in Saccharomyces cerevisiae.
Published: 2006
Language: eng
Number of pages: 206
ISBN-13: 9780494217757
Description: The Cys2-His2 zinc finger is a well-characterized DNA-binding domain that derives its structure from the coordination of a central zinc ion by two cysteine and two histidine residues. My thesis research addressed the role of Cys2-His2 zinc finger-containing proteins in the regulation of gene expression at two promoters in Saccharomyces cerevisiae.In Chapter 3, I describe the role of two Cys2-His2 zinc finger proteins, Rim101 and Nrg1, in the negative regulation of the  DIT1 and DIT2 genes. These divergently-transcribed mid-late sporulation-specific genes are repressed during mitotic growth in a manner that depends on the Ssn6-Tup1 repressor complex and on a negative regulatory element (NRE) present in the intergenic region. The studies described in this Chapter demonstrate that Nrg1 and Rim101 bind to distinct subsites within the bipartite NRE and act as corepressors at the DIT promoter. Rim101-dependent repression through the NRE depends on an upstream RIM signaling pathway that regulates the proteolytic activation of Rim101. My studies also identify Dfg16, Ygr122w and components of the ESCRT trafficking pathway as additional regulators of both Rim101 processing and Rim101-dependent repression of the DIT genes.Chapter 2 presents my analysis of the contribution of individual zinc fingers of transcription factor (TF) IIIA to the assembly of an initiation complex at the 5S RNA gene. TFIIIA, an RNA polymerase III transcription factor that contains nine Cys2-His2 zinc-fingers, binds to the internal control region (ICR) of the 5S RNA gene as the first step in the assembly of a TFIIIB-TFIIIC-TFIIIA-DNA initiation complex. My studies highlight a critical role for zinc finger seven and for residues F50 and Y53 in the first zinc finger of TFIIIA in the establishment of a functional initiation complex at the 5S RNA gene. Versions of TFIIIA containing structural disruption of either zinc finger one or seven, or a version of TFIIIA containing simultaneous mutation of residues F50 and Y53 are unable to support in vitro transcription of the 5S RNA gene or to support cell viability. Simultaneous disruption of both zinc finger four and six also abolishes the ability of TFIIIA to support cell viability.
Notes: Source: Dissertation Abstracts International, Volume: 68-01, Section: B, page: 0279.

Thesis (Ph.D.)--University of Toronto, 2006.

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