Comparison of expression profile among the substrains in cyanobacterium Synechocystis sp. PCC 6803

The cyanobacterium Synechocystis sp. PCC 6803 (S. 6803) has been studied as a model organism for photosynthesis research. However, there are several wild-type strains (laboratory strains) of S. 6803 with different phenotypes, such as glucose utilization and phototaxis, which need to be carefully considered when using S. 6803 in research. In order to characterize the S. 6803 laboratory strains, the expression profile was compared among three S. 6803 strains, GT-In, PCC-Pn, and PCC-Mn.Compared with the GT-In strain, the PCC-Pn strain showed different gene expression patterns that could explain the phenotypic differences, including a group of sulfate polysaccharide synthesis genes encoded in plasmid pSYSM and genes involved in CO2 uptake. In the genes shown the significant differences of gene expression among laboratory strains, we focused on the slr6050 gene, encoding methyltransferase in the plasmid pSYSX. The overexpression of slr6050 partially suppressed the glucose sensitivity in PCC-Pn strain, suggesting the involvement of plasmid to the phenotype among laboratory strains.