Abstract

PHO13 in Saccharomyces cerevisiae (budding yeast) is a para-nitrophenyl phosphatase (pNppase) of the haloacid dehalogenase (HAD) superfamily. A biological substrate for PHO13 had remained undiscovered while a knockout phenotype has only been observed in strains engineered to grow on D-xylose. The purified enzyme has been identified in our lab to specifically hydrolyze 2-phosphoglycolate, classifying it as a phosphoglycolate phosphatase (PGPase). In photosynthetic organisms, 2-phosphoglycolate (2-PG) is generated by the oxygenation reaction of ribulose-1,5-bisphosphate carboxylase (RuBisCO) in the Calvin Cycle. To be recycled back into general metabolism, photosynthetic PGPase converts 2-PG to glycolate. In non-photosynthetic yeast, 2-PG must be generated by some other mechanism, possibly by DNA oxidative damage, but would nonetheless need to be catabolized due to its ability to inhibit triose phosphate isomerase (TPI). Yeast cells lacking functional Pho13p (pho13Δ) were investigated for phenotypes that support TPI1 inhibition including the ability to adapt in the presence of hyperosmotic media (1M NaCl) and the inability to grow in the absence of inositol. Cells lacking Pho13p did not exhibit an obvious phenotype under either condition. To increase intracellular levels of 2-PG, cells were additionally treated with hydrogen peroxide. The pho13Δ strain appeared to exhibit a hypersensitive growth phenotype in the presence of hydrogen peroxide when grown under limiting nutrient conditions. However, when complementation was attempted with this phenotype, variability was observed among pho13Δ strains using different expression vectors.

Library of Congress Subject Headings

Phosphatases--Analysis; Saccharomyces cerevisiae--Genetics; Phenotype

Publication Date

5-2016

Document Type

Thesis

Student Type

Graduate

Degree Name

Chemistry (MS)

Department, Program, or Center

School of Chemistry and Materials Science (COS)

Advisor

Austin Gehret

Advisor/Committee Member

Suzanne O’Handley

Advisor/Committee Member

Lea Michel

Comments

Physical copy available from RIT's Wallace Library at QP609.P5 K45 2016

Campus

RIT – Main Campus

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