Stromal Chaperone Proteins in Disaggregation and Insertion of Light-Harvesting Chlorophyll-Binding Proteins

Date of Award


Degree Name

Master of Science


Biological Sciences

First Advisor

Yan Lu, Ph.D.

Second Advisor

Todd Barkman, Ph.D.

Third Advisor

Silvia Rossbach, Ph.D.


Chaperone protein, chloroplast, light-harvesting chlorophyll-binding proteins, photosynthesis

Access Setting

Masters Thesis-Abstract Only

Restricted to Campus until



Light-harvesting chlorophyll-binding proteins (LHCPs) are crucial for photosynthesis in plants. Their proper localization in the thylakoid membrane requires the coordination of multiple protein chaperones during their import and assembly in the chloroplast. In this study, we investigated the role of stromal (co)chaperones DJA4/5/6/7 in the import, delivery, disaggregation, and thylakoid membrane integration of LHCPs in Arabidopsis thaliana. Using a series of biochemical assays, we found that the loss of individual DJA proteins led to reduced health of mutants in several key biomarkers, as well as levels of LHCPs in the thylakoid membrane, while the loss of multiple DJAs had a more severe effect on overall plant health and LHCP localization. We also observed that cpHSC70-1/2, cpHSP90C, and cpGrpE1/2 are involved in the same process. Based on these data, an alternative pathway for LHCP import and thylakoid membrane insertion has been proposed, involving the concerted action of stromal DJAs, cpHSC70-1/2, cpHSP90C, and cpGrpE1/2. Our findings shed light on the mechanism of chloroplast protein import and assembly, and have important implications for understanding the regulation of photosynthesis in plants.

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