リポ酸要求性大腸菌変異株の生化学的性状 Some Properties of a Mutant Strain of Escherichia coli Requiring Lipoic Acid
A mutant strain of Escherichia coli, O8-442,requiring lipoic acid (LiA) for both aerobic and anaerobic growth in a minimal medium with glucose as a sole carbon source was isolated. The requirment for LiA could be replaceable by either acetate+succinate or acetate+lysine+methionine under aerobic conditions, but anaerobically it grew on either acetate or succinate alone. Pyruvate markedly stimu1ated.the respiration of the mutant cells grown aerobically on LiA and the addition of LiA did not cause a further stimulation. Conversely, results obtained with the cells grown aerobically on acetate+ lysine+methionine was quite different ; the degree of the pyruvate-oxidizing activity was very low but the activity was fully restored by the addition of LiA. In the same system, lipoamide (LiANH_2) was found to have no activity for the respiration of the mutant cells, while it was more active than LiA when extracts prepared from the mutant cells were used. These results suggest that the de novo synthesis of LiA is blocked in the mutant strain. A permeability barrier appears to be involved in the utilization of LiANH_2.
ビタミン 48(9), 453-462, 1974