FIGURE 3.

Characterization of the E. coli ΔygfA mutant. A, deletion of ygfA causes a 6-fold increase in cellular 5-CHO-THF content, significant at p < 0.05 by t test (asterisk). Folate analysis was performed on E. coli wild-type (WT) and deletant (ΔygfA) cells grown on M9 minimal medium supplemented with 0.2% glucose and 7 mm glycine. Data are means and S.E. from three replicates. 10-CHO-DHF, 10-formyldihydrofolate; other folate abbreviations are as in the legend to Fig. 1 and the abbreviations footnote. B, growth phenotype of the ΔygfA deletant. E. coli wild type or ΔygfA cells transformed with pBS II SK alone or harboring ygfA were plated on minimal medium containing either 20 mm NH₄Cl or 50 mm glycine as sole nitrogen source. Plates were incubated for 3 days.