Repression of Inducible Tartrate Dehydratases in Pseudomonas Strains

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Abstract
The effect of various growth substrates on the synthesis of three inducible enzymes (the stereo-specific tartrate dehydratases) has been followed in strains of Pseudomonas. Four organic acids (succinate, malate, acetate, meso-tartrate) inhibited induction of some or of all of the tartrate dehydratases, while three (pyruvate, l-tartrate and d-tartrate) did not inhibit. Whenever inhibition occurred, synthesis of d- and 1-tartrate dehydratase was repressed much more strongly than synthesis of meso-tartrate dehydratase. Pre-induction of the bacteria did not prevent subsequent repression, and a degree of correlation was found between the growth rate supported by substrates and the extent of repression. The significance of the different degrees of repression given by substrates feeding into closely related sites of the Krebs cycle and of the differences in repression exerted on enzymes acting on closely related compounds is discussed.