Protein Expression in Synechococcus PCC 7002: A Quantitative Comparison of Promoters and Integration Sites

Photosynthetic Cyanobacteria can be used as a chassis for different synthetic biology approaches. However, quantitative comparison of tools for engineering, such as those for heterologous gene expression, is often not available. Here, we report the comparative quantification of heterologous protein production in Synechococcussp.PCC 7002 regarding protein expression cassettes and locations of foreign gene integration using sf-GFP as a reporter. We used promoter cpc560 as reference because it was described as a "super strong" promoter. sf-GFP-expression constructs were integrated into neutral sites NS_1, NS_2, NS_3 and the extrachromosomal plasmid pAQ1. The latter induced a sf-GFP level of approximately 10-fold in comparison to a reference promotor expression. Protein-fusion with 6xHis increased sf-GFP as well as expression of sf-GFP fusion with ß subunit of phycocyanin.