FIG. 1.

Transcription of hla in COL and its isogenic mutants. (A) Northern blot analysis of hla. RNA was harvested from cells grown to an OD₆₅₀ of 1.7 (OD1.7) at a time when hla expression was expected to be the strongest. One typical blot with RNA with an OD₆₅₀ of 1.7 is shown. An RNA gel below shows equal sample loadings. wt, wild type. (B) The expression of GFP driven by the hla promoter was measured. The fluorescence and cell density (OD₆₅₀) were measured hourly for 10 h and then overnight by transferring aliquots (200 μl) to microtiter plates in triplicate. The results from one time point (8 h; OD₆₅₀ of 1.7) of promoter activation are shown and are plotted as mean fluorescence divided by the OD₆₅₀ using average values from triplicate readings.