Towards a biochemical characterization of the diatom pyrenoid

The key photosynthetic CO2-fixing enzyme, Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), generally possesses a poor catalytic rate. It is also susceptible to a side-reaction with oxygen and forms dead-end inhibited complexes with sugar phosphates. Increasing the CO2 concentration at the...

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Main Author: Oh, Zhen Guo
Other Authors: Oliver Mueller-Cajar
Format: Thesis-Doctor of Philosophy
Language:English
Published: Nanyang Technological University 2020
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Online Access:https://hdl.handle.net/10356/137338
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spelling sg-ntu-dr.10356-1373382023-02-28T18:30:46Z Towards a biochemical characterization of the diatom pyrenoid Oh, Zhen Guo Oliver Mueller-Cajar School of Biological Sciences cajar@ntu.edu.sg Science::Biological sciences The key photosynthetic CO2-fixing enzyme, Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), generally possesses a poor catalytic rate. It is also susceptible to a side-reaction with oxygen and forms dead-end inhibited complexes with sugar phosphates. Increasing the CO2 concentration at the Rubisco active site can counter these drawbacks. Most marine phytoplankton possess a carbon dioxide concentrating mechanism (CCM), which uses active transport to saturate the Rubisco active site with its gaseous substrate. A key component of this CCM is a non-membranous Rubisco compartment within the chloroplast stroma known as the pyrenoid. This study initiated a biochemical chacterization of the pyrenoid of the model diatom, Phaeodactylum tricornutum. Pyrenoid Factor 1 (Pf1) is an intrinsically disordered repeat protein that was identified through co-immunoprecipitation of P. tricornutum Rubisco and shown to localize to the pyrenoid. Pure recombinant Pf1 underwent homotypic liquid liquid phase separation (LLPS) to form condensates that specifically partitioned diatom Rubisco. Gel-shift assays involving Pf1 fragments and multiple chimeric Rubisco variants demonstrated that the proteins interact via repeated Pf1 KWSPR/Q motif and the Rubisco small subunit. These results contribute to our understanding of the convergent evolution of pyrenoid in diverse eukaryotic algae. Further definition of the components and interactions governing the assembly of the red-lineage phytoplankton pyrenoid will empower our ability to enhance carbon fixation in future crops. Doctor of Philosophy 2020-03-18T04:54:38Z 2020-03-18T04:54:38Z 2019 Thesis-Doctor of Philosophy Oh, Z. G. (2019). Towards a biochemical characterization of the diatom pyrenoid. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/137338 10.32657/10356/137338 en This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). application/pdf Nanyang Technological University
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Biological sciences
spellingShingle Science::Biological sciences
Oh, Zhen Guo
Towards a biochemical characterization of the diatom pyrenoid
description The key photosynthetic CO2-fixing enzyme, Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), generally possesses a poor catalytic rate. It is also susceptible to a side-reaction with oxygen and forms dead-end inhibited complexes with sugar phosphates. Increasing the CO2 concentration at the Rubisco active site can counter these drawbacks. Most marine phytoplankton possess a carbon dioxide concentrating mechanism (CCM), which uses active transport to saturate the Rubisco active site with its gaseous substrate. A key component of this CCM is a non-membranous Rubisco compartment within the chloroplast stroma known as the pyrenoid. This study initiated a biochemical chacterization of the pyrenoid of the model diatom, Phaeodactylum tricornutum. Pyrenoid Factor 1 (Pf1) is an intrinsically disordered repeat protein that was identified through co-immunoprecipitation of P. tricornutum Rubisco and shown to localize to the pyrenoid. Pure recombinant Pf1 underwent homotypic liquid liquid phase separation (LLPS) to form condensates that specifically partitioned diatom Rubisco. Gel-shift assays involving Pf1 fragments and multiple chimeric Rubisco variants demonstrated that the proteins interact via repeated Pf1 KWSPR/Q motif and the Rubisco small subunit. These results contribute to our understanding of the convergent evolution of pyrenoid in diverse eukaryotic algae. Further definition of the components and interactions governing the assembly of the red-lineage phytoplankton pyrenoid will empower our ability to enhance carbon fixation in future crops.
author2 Oliver Mueller-Cajar
author_facet Oliver Mueller-Cajar
Oh, Zhen Guo
format Thesis-Doctor of Philosophy
author Oh, Zhen Guo
author_sort Oh, Zhen Guo
title Towards a biochemical characterization of the diatom pyrenoid
title_short Towards a biochemical characterization of the diatom pyrenoid
title_full Towards a biochemical characterization of the diatom pyrenoid
title_fullStr Towards a biochemical characterization of the diatom pyrenoid
title_full_unstemmed Towards a biochemical characterization of the diatom pyrenoid
title_sort towards a biochemical characterization of the diatom pyrenoid
publisher Nanyang Technological University
publishDate 2020
url https://hdl.handle.net/10356/137338
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