Abstract
Escherichia coli mutant strains, 64-21 and 42-11,both requiring either high concentrations of hydroxymethylpyrimidine or low concentrations of thiamine, have been produced by further mutation of a mutant strain, 26-43,requiring the thiazole moiety of thiamine. The concentration of hydroxymethylpyrimidine required for a half-maximal growth of the respective organisms was approximately 10,000 and 1,000 times higher than that of thiamine required for the same extent of growth. Experimental results showed that phosphomethylpyrimidine kinase activity was deficient in these mutant cells and that they could not take up hydroxymethylpyrimidine into the cells in a significant amount when it was supplied at the concentrations less than 0.01mM. Another mutant, 70-23,lacking in phosphomethylpyrimidine kinase activity, could not also take up hydroxymethylpyrimidine. Some role of phosphomethylpyrimidine kinase in the uptake of hydroxymethylpyrimidine in Escherichia coli was discussed.
