Figure 2.

Analysis of isolated terminator sequences. (A) Activity test of the β-galactosidase reporter gene, indicating transcriptional read-through for isolated terminator constructs that leads to gene expression in the absence of theophylline. The positive control bgaBU₈ is a construct lacking the terminator hairpin but still carries the U₈ stretch. Activities are given in Miller Units. (B) Northern blot analysis of full-length β-galactosidase mRNA from terminator constructs. As internal control, the hybridization signal for 23S rRNA is shown. Asterisks indicate the position of mRNA signals where a sufficient amount of transcriptional read-though occurred. (C) Predicted energy barriers for terminator formation in the individual constructs in kcal/mol. Barriers were computed using the Pathfinder algorithm.²¹ Constructs with high formation barriers (T10loopA, T8, T8ΔCU) are predicted to get trapped in a meta-stable state.