Effects of inorganic carbon limitation in wild-type and carbon sink mutants of the cyanobacterium Synechocystis sp. PCC 6803

Abstract

The efficiency of photosynthetic electron transport is an important factor in the cellular metabolism of photosynthetic organisms. The high energy molecules produced in the light reactions of photosynthesis are used to energize the reactions of the Calvin-Benson-Bassham cycle and assimilate inorganic carbon into central metabolism. Impaired electron transport can lead to photodamage and the creation of damaging oxygen radical species. The redox state of electron carrier molecules also provides regulatory feedback to a wide range of metabolic pathways and cellular functions. It is therefore important to understand the response of photosynthetic organisms to conditions where electron transport may be hindered.

Since inorganic carbon uptake and utilization is important in cellular metabolism as well as bio-engineering projects, further understanding of the interconnectedness of carbon uptake and photosynthesis is needed. This project first explores the effect of inorganic carbon limitation on the redox state of the photosynthetic electron transport chain and reductant pools. Then understanding how alterations in carbon sink availability affect photosynthetic efficiency and acclimation to low inorganic carbon availability is explored. The results provide a background for the analysis of carbon utilization and photosynthetic efficiency in future bio-engineering efforts.