Figure 5

Promoter activities per cell under non-induced (0 mM IPTG) and induced (1 mM IPTG) conditions, characterized using an EYFP reporter construct carried on pPMQAK1 [25]in an engineered Synechocystis PCC 6803 strain expressing LacI (this work). A. Control promoters. J23101 corresponds to BioBrick BBa_J23101 (iGEM Registry [34]) and is a constitutive control promoter without lac operator (lacO). Ptrc 2O-original is the Ptrc 2O version previously characterized [25] with lacO1 in the proximal position and the symmetric lacO (lacO sym) in the distal position. Ptrc 1O-distal,-core, and-proximal are Ptrc-derived promoters with only one lacO sym at the indicated position. PA1lacO-1 is a previously used promoter with lacO in the core and proximal positions [36]. B. The Ptrc 2O-library. The length of the spacer sequence between the−35 box and the distal lacO sym is indicated on the upper x-axis and the distance between the two lacO sym is indicated on the lower x-axis. Promoter activities per cell are given in fluorescence/absorbance at 750 nm in arbitrary units [AU]. Broken line columns represent promoter activity per cell for the corresponding promoter tested in the chloramphenicol resistance-only strain of Synechocystis (LacI negative, this work). Error bars indicate standard error of the mean for the Synechocystis PCC 6803 strain expressing LacI (n = 4) and the chloramphenicol resistance-only Synechocystis strain (n = 2). The numbers on top of the normal columns are the induction ratios, the numbers in parenthesis on top of the broken columns are the repression ratios. IPTG, Isopropyl β-D-1-thiogalactopyranoside.