COG3643 in relation to the Hut pathway. (A) Hut pathway; note the three different routes. (B) The distribution of histidine utilization genes among bacterial and eukaryal genomes in relation to that of the ygfA gene for 5-formyltetrahydrofolate disposal. Gene colors correspond to different parts of the pathway as in part A. Lines between boxes denote gene fusions. (C) Growth of an E. coli ygfA deletant harboring plasmid-borne E. coli ygfA, Acidobacterium COG3643, or vector alone on minimal medium with NH4Cl or glycine as sole nitrogen source. The medium contained 1 mM IPTG and appropriate antibiotics.