THE LIGHT GREEN PHENOTYPE 1 PROTEIN IS REQUIRED FOR PHOTOSYSTEM I-LIGHT HARVESTING COMPLEX ASSEMBLY IN CHLAMYDOMONAS REINHARDTII
Date
2020-01-24
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0001-5687-3319
Type
Thesis
Degree Level
Masters
Abstract
In the green alga Chlamydomonas reinhardtii, the light harvesting (LHC) proteins form a dynamic complex that regulates the amount of light energy being absorbed by the cell and transmitted to the photosynthetic reaction centers. Because resonance energy transfer efficiency declines with distance between chlorophyll molecules, the organization of the LHC proteins is critical for the process of energy transmission. Studies have suggested that LHC organization requires the assistance of chaperone-type assembly factors, but to date none have been identified. In this study we used a high-light sensitive psaF mutant to identify a LHC assembly-factor candidate. The mutant identified had a light green phenotype (lgp1). The cells accumulate approximately 66% of wild-type chlorophyll levels, with an elevated Chl a/b, suggesting LHC abundance. Steady-state chlorophyll fluorescence measurements suggest a moderate impact on photosynthetic function with a decline in electron flow from PSII to PSI. A semi-quantitative assessment of individual LHC subunits found that all LHC proteins accumulated at lower levels except for LHCA8, LHCB2 and LHCBM5. By Blue-Native Gel (BN) electrophoresis, it was discovered that high molecular weight PSII-LHC complexes were missing in lgp1. This was confirmed using 2D-PAGE. Our introductory analysis suggests that the LGP1 protein is involved in connecting specific LHC proteins to PSII. We are working to confirm this by examining protein-protein interactions between LGP1, PSII, and the diminished LHC proteins. If confirmed, LGP1 would be the first LHC assembly-factor identified in C. reinhardtii.
Description
Keywords
C. reinhardtii, Photosynthesis
Citation
Degree
Master of Science (M.Sc.)
Department
Biology
Program
Biology