Discovery of nitrogen starvation detecting and signaling mutants in Chlamydomonas reinhardtii
department or school: Science, Faculty of
data provider: DSpace
degree campus: UBCV
creator: Munz, Jacob Alexander
issued: 2022-04-30T07:00:00Z
issued: 2020
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: Nitrogen (N) is a fundamental macronutrient that constitutes nucleic/amino acids. Therefore, organisms require signaling mechanisms to sense external and internal N and regulate essential processes like cell growth, development, and energy metabolism. The responses to changes in cellular N status in bacteria/fungi are mediated by monitoring metabolites of the N assimilation pathway ending with glutamine synthetase (GS) and glutamate synthase (GOGAT) enzymes, forming the GS/GOGAT cycle. In photosynthetic eukaryotes, N assimilation relies on the GS/GOGAT cycle, however, whether similar signaling mechanisms are operant remains unknown. Breakthroughs in the N status signaling of bacteria/fungi were made by utilizing N sources that activated N starvation responses during growth, defined as 'derepressive'. While it is known that NH₄⁺ and NO₃- repress N starvation responses in photosynthetic eukaryotes, no derepressive N sources have been established. The unicellular green alga, Chlamydomonas reinhardtii, can survive on a wider array of N sources than land plants, of which arginine-feeding was known to derepress gametogenesis, a N starvation-specific response. This work investigated the use of arginine as a derepressive N source in photosynthetic eukaryotes and documented that N starvation responses were activated (Chapter 3 and 4). Using this derepressive condition, screens for defective N starvation responses collected mutants displaying nitrogen insensitivity (nsi) or constitutive nitrogen starvation responses (cns). Five nsi mutants disrupted the same region, NSI1, encoding a divergent glutamine synthetase (GLN4) (Chapter 5). NSI1 homologs were found in chlorophytes, and sequence features common to this family suggested it is unlikely to catalyze the reduction of NH₄⁺ but may detect N status via its potential binding to glutamate (Chapter 5). The cns mutants suggested a negative regulation of N starvation responses, whose further study may elucidate how NH₄⁺ rapidly re…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/74262
note: DISCOVERY OF NITROGEN STARVATION DETECTING AND SIGNALING MUTANTS IN CHLAMYDOMONAS REINHARDTII by Jacob Alexander Munz B.Sc., Colorado State University, 2011 M.Sc., Illinois State University, 2014 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (BOTANY) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) April 2020 © Jacob Alexander Munz, 2020 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, the dissertation entitled: Discovery of nitrogen starvation detecting and signaling mutants in Chlamydomonas reinhardtii submitted by Jacob Munz in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Botany Examining Committee: Jae-Hyeok Lee, Professor, Botany, UBC Supervisor George Haughn, Professor, Botany, UBC Supervisory Committee Member Robert Guy, Professor, Forestry, UBC University Examiner Yuelin Zhang, Professor, Botany, UBC University Examiner iii Abstract Nitrogen (N) is a fundamental macronutrient that constitutes nucleic/amino acids. Therefore, organisms require signaling mechanisms to sense external and internal N and regulate essential processes like cell growth, development, and energy metabolism. The responses to changes in cellular N status in bacteria/fungi are mediated by monitoring metabolites of the N assimilation pathway ending with glutamine synthetase (GS) and glutamate synthase (GOGAT) enzymes, forming the GS/GOGAT cycle. In photosynthetic eukaryotes, N assimilation relies on the GS/GOGAT cycle, however, whether similar signaling mechanisms are operant remains unknown. Breakthroughs in the N status signaling of bacteria/fungi were made by utilizing N sources that activated N starvation responses during growth, defined as 'derepressive'. While it is known that NH4+ and NO3- repress N starvation responses in photosynthetic eukaryotes, no d…
has type: Thesis/Dissertation
date issued: 2020-05
is shown at: 10.14288/1.0390287
language: eng
degree discipline: Botany
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/74262