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Title: Elucidating the Dynamics of Pyrenoid Biogenesis Through Intergenic Suppression of saga1
Authors: Kayser-Browne, Angelo
Advisors: Jonikas, Martin C
Department: Molecular Biology
Certificate Program: Global Health and Health Policy Program
Class Year: 2022
Abstract: The enzyme Rubisco drives the fixation of atmospheric carbon into organic compounds, and the growth of photoautotrophic organisms is inherently dependent on Rubisco-CO2 kinetics. Algae provide Rubisco with concentrated CO2 at the pyrenoid, an organelle within the chloroplast which drives one-third of global carbon fixation. The biogeochemical significance of the pyrenoid makes it a promising bioengineering target, necessitating an understanding of the genes involved in pyrenoid biogenesis. In the alga Chlamydomonas reinhardtii, the gene SAGA1 is required for normal growth and pyrenoid formation, and knockout leads to severely limited growth in air and the formation of multiple pyrenoids with key structural defects. The multifaceted nature of this mutant phenotype suggests that numerous genes may be misregulated in the absence of SAGA1, collectively leading to the observed changes in pyrenoid morphology and growth. However, the identities of these genes and their relationships to SAGA1 are largely unknown. We performed a suppressor screen to determine if the knockout of certain genes could rescue the saga1 mutant. A subset of suppressor mutants showed partial recovery of wild-type features, including improvements in pyrenoid morphology and the ability to grow in air. Our efforts provide quantitative phenotypic information on these mutants and lend credence to a model in which canonical pyrenoid formation is at least partly dependent on the presence of a tubule network and precise phosphorylation of the linker protein EPYC1. Given the implications of pyrenoid formation on carbon fixation as a whole, these results represent a crucial step toward the realization of bioengineered CCMs in crops to address burgeoning concerns in agriculture and climatology.
Type of Material: Princeton University Senior Theses
Language: en
Appears in Collections:Molecular Biology, 1954-2022
Global Health and Health Policy Program, 2017-2022

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