Overexpression of NblA decreases phycobilisome content and enhances photosynthetic growth of the cyanobacterium Synechococcus elongatus PCC 7942

Abstract

Many research groups have considered whether decreasing photosynthetic antenna content in cyanobacteria can improve photosynthetic oxygen evolution and biomass accumulation. We describe a genetic strategy for truncating light harvesting antennae based on engineered alterations in the expression of NblA, a native protein naturally used by cyanobacteria to disassemble phycobilisomes antennae in response to environmental changes. We show that if enforced overexpression is fine-tuned, it is possible to realize gains in photosynthesis in a model cyanobacterium Synechococcus elongatus PCC 7942. We also show that antennae truncation helps protect cells from photodamage and that a strain overexpressing NblA can outcompete wild type in a mixed population. We propose approaches for future applications of these findings.