Proteins destined for the thylakoid lumen of plant chloroplasts are nuclear encoded as higher molecular weight precursors containing transit peptides that target the protein to their final destination. The chloroplast twin arginine translocation (cpTat) pathway of thylakoid is responsible for transport of ~50% of the proteins destined for the lumen. The cpTat pathway is unique because it transports folded proteins relying solely on the photosynthetic protonmotive force (pmf) for energy. Three membrane-bound proteins are required in land plants for this transport process: Tha4, Hcf106, and cpTatC. cpTatC and Hcf106 serve as the precursor receptor, while Tha4 is initially found in a separate complex. Upon generation of a pmf, i.e., upon illumination, and in the presence of a precursor, Tha4 oligomers assemble with the precursor-bound receptor complex. At this point translocation of precursor occurs. After translocation, the cpTat complex disassembles thus resetting the system for subsequent rounds of translocation. To-date, this process has been minimally studied in algae. Here, we present data demonstrating the cross-reactivity of antibodies derived against the garden pea, Pisum sativum, cpTat proteins, Tha4 and Hcf106, with cell extracts from Coccomyxa subellipsoides and Chlorella vulgaris. Crossreactivity opens up avenues to investigate the function of cpTat in algae. Fundamental understanding of these proteins in C. subellisoides and C. vulgaris algae may provide knowledge of the assembly of photosynthetic machinery, provide advantages to increase biomass, and possible generation of commercial molecules (biofuels, pharmaceuticals).

Cross-reactivity of antibodies derived against Pisum sativum (a land plant) proteins, Tha4 and Hcf106, with cell extracts from the algae Coccomyxa subellipsoides and Chlorella vulgaris

247th National Meeting (2014)

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