Action of a proline analogue, l-thiazolidine-4-carboxylic acid, in Escherichia coli.

Unger, Leon (University of Illinois, Urbana), and R. D. DeMoss. Action of a proline analogue, l-thiazolidine-4-carboxylic acid, in Escherichia coli. J. Bacteriol. 91:1556-1563. 1966.-The effect of the proline analogue, l-thiazolidine-4-carboxylic acid (thioproline), on growth, and its relation to the metabolic function of proline in protein synthesis in Escherichia coli K-12, has been studied. Thioproline causes linear growth in E. coli within one generation. The inhibition is specifically reversed by the simultaneous addition of l-proline. Thioproline, or a closely related metabolic derivative, is incorporated into bacterial proteins. Proline antagonizes the incorporation of "thioproline" into protein. The analogue specifically inhibits the rate and extent of prolyl-ribonucleic acid formation. The effectiveness of thioproline as a proline analogue is attributed to its ability to interfere with the utilization of proline for protein synthesis and to mimic proline in its function of being incorporated into proteins. The effect of the incorporation of thioproline on protein structure and enzyme activity is discussed.