A subpool of the large subunit of ribulose bisphosphate carboxylase-oxygenase has a dual function in oxidative stress tolerance in Chlamydomonas reinhardtii
Year: 2013
Type: dissertation
Abstract: A subpool of the large subunit of ribulose bisphosphate carboxylase-oxygenase has a dual function in oxidative stress tolerance in Chlamydomonas reinhardtii Jamieson Dhaliwal Stress granules (SGs) are cytoplasmic foci of mRNA and protein that form in eukaryotic cells during stress-induced translational arrest.Similar structures called chloroplast stress granules (cpSGs) are found in the chloroplast stroma of Chlamydomonas reinhardtii.Unique to cpSGs is the presence of a photosynthesis protein, the large subunit of Rubisco (RBCL).It was found that an RBCL-deficient mutant of Chlamydomonas has impaired oxidative stress tolerance, while a mutant that retains RBCL in the absence of the Rubisco holoenzyme has improved oxidative stress tolerance.Through genetic analyses, I show that these opposing effects are RBCL-dependant, demonstrating a dual function for RBCL in controlling oxidative stress tolerance.I then provide evidence, through biochemical analyses, for the existence of a subpool of RBCL that carries out this dual function independently of Rubisco enzymatic activities.This RBCL subpool is found to have altered properties from that of Rubisco, which may be consistent with its recruitment to cpSGs.Because the oxidation of specific biological molecules is thought to contribute to cell death during oxidative stress, I then explore a function of RBCL in controlling molecular oxidative damage.I show that RBCL is not required for the prevention of oxidative damage to protein.This result supports the finding that RBCL is able to prevent the acuumulation of oxidized RNA.Though specific to RBCL, these findings may reflect functions of cpSGs and even SGs.
Author: Jamieson Dhaliwal
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W91034566