FIG 4.

Quantification of 2-OG levels in the wild type and the ΔtrpE mutant (UHM335) under various conditions. (A) The wild type (circles) and UHM335 (circles) were grown in BG-11 medium containing ammonia (NH₄) and stepped down to growth on nitrate (NO₂). (B) The wild type was grown in nitrate supplemented with 10 μM AZAT (solid line), 100 μM dl-tryptophan (dashed line), or nothing (dotted line). (C) The wild type (circles) and UHM335 (circles) were stepped down from nitrate-containing growth medium to that lacking a source of combined nitrogen. The 0-h time point corresponds to the time of the step down or the addition of amino acids. 2-OG was quantified in triplicate at the time points shown. Error bars represent standard deviations.