Cloning and partial characterization of the novel BLM3 gene.
Item
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Title
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Cloning and partial characterization of the novel BLM3 gene.
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Identifier
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AAI3024784
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identifier
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3024784
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Creator
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Evans Febres, Donna Marie.
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Contributor
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Adviser: Carol Wood Moore
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Genetics | Biology, Molecular
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Abstract
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Mutational alteration of the BLM3 gene in Saccharomyces cerevisiae confers hypersensitivity to lethal effects of ionizing radiation, bleomycin and structurally-related phleomycin. Bleomycin is an anticancer drug used clinically in the treatment of many types of cancers. In the absence of bleomycin or structurally-related phleomycin, the blm3-1 mutant cells were smaller in size, grew more slowly than BLM3 cells, and displayed decreased viability. Preliminary studies showed that the viability of mutant cells was enhanced after exposure to 2 M cations (Na+, K+) and 0.005% sodium dodecyl sulfate (SDS), while the viability of BLM3 cells decreased after these exposures. The enhanced viability of mutant cells suggested an alteration in membrane integrity. The BLM3 gene was cloned by functional complementation of the phleomycin hypersensitivity conferred by the blm3-1 mutation. The nucleotide sequence of BLM3 encodes a predicted integral protein of 1804 amino acids with seven to ten potential transmembrane domains and additional motifs. The null mutant, blm3Delta::HIS3, was created by gene replacement. In the absence of the bleomycin-phleomycin group of antibiotics, the BLM3 gene is not essential for viability. Mutant blm3Delta::HIS3 cells in the absence of bleomycin and structurally-related phleomycin were not significantly smaller in size, grew only slightly slower than related BLM3 cells, and did not display decreased viability. Preliminary studies showed that the viability of mutant blm3Delta::HIS3 cells was not enhanced after exposure to 2 M cations (Na+, K+) and 0.005% SDS compared to the viability of related BLM3 cells. Based on preliminary localization studies, Blm3p appeared to be localized around the cell surface. Based on all of these studies, we propose that Blm3p may play a role in structural integrity of the plasma membrane, cellular growth, and membrane permeability. The possible role of Blm3p as a transporter is also discussed.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
