Updated project metadata. Using an engineered 3-HP producing SM strain, in this project, the cellular responses to 3-HP internally produced were first determined using a quantitative iTRAQ-LC-MS/MS proteomics approach. A total of 2,264 unique proteins were identified, which represented about 63% of all predicted protein in Synechocystis in the proteomic analysis of the 3-HP producing strain SM and wild type. Among all identified proteins, 204 proteins were found up- regulated and 123 proteins were found down-regulated, respectively. The proteins related to oxidative phosphorylation, photosynthesis, ribosome, central carbon metabolism, two-component systems and ABC-type transporters were up-regulated. The results suggested that the supply of ATP and NADPH was increased significantly, and the precursor malonyl-CoA and acetyl-CoA may also be supplemented when 3-HP was produced at a high level in Synechocystis.