42

4                             tliochsmisily
THB INDUCTION OF IWO SIMILAR ENZYPIES BY ONll INDUCBB. A Tl3ST
CASE POR SlIABeD GENETIC INwaMATIoN.  Marshall W. Nfrenber&
(intr. W. B. Jakoby.) Natl. Insts. of Health, Bethesda, Md.
This investigation asks whether a portion of one gene con-
tains information for the synthesis of a protein subunit which
might be an integral part of two or more enzymes.  A strain of

Pseudomonas fluorescens formed an inducible 7-hydroxybutyric
acid dehydrogenase (ReactIon 1) when growl upon y-hydroxy-
butyric acid-(7-l&, and an inducibl; D-hydroxypropionic acid
dehydrogenaae (Reaction 2) when grown upon g-hydroxypropionlc
acid (D-DPA) Nirenbcrg, H. W. and Jakoby, W. B., J. Biol. Chem.
(In press.)
1) 7-lfP.A+DPNe Succfnic Semfaldehyde + DPNIi + lI+
2) +HPA + DPN e Malonic Semfaldehyde + DPND + H'
An attempt was made to induce the reversible pEBA dehydro-
genaae by both the reactant and the product of the reaction;
only 7-DDA was effective.  A series of mutant strains blocked
in reaction 1 were obtained.  Strikingly high ,WiF+A dehydro-
genase levels were found in these strains when 7-BBA was added.
Analysis demonstrated that 7-HBA at low concentrations induced
the formatfon of 7-DIV. dehydrogenase, and, at higher concen-
trations, induced the formation of both 7-DBA and D-EPA
dehydrogenases.  Genetic information did not appear to be
shared; instead 7-DBA was found to serve as an inducer for two
similar enzymes in different metabolic pathways.