Subject(s)
Aconitate Hydratase/metabolism , Fluoroacetates/pharmacology , Hot Temperature , Hydro-Lyases/metabolism , Radiation-Protective Agents/pharmacology , Aconitate Hydratase/antagonists & inhibitors , Animals , Body Temperature/drug effects , Citrates/biosynthesis , Fluorine/biosynthesis , Heart/physiology , In Vitro Techniques , Kidney/enzymology , Kidney/physiology , Liver/enzymology , Liver/physiology , Male , Mice , Myocardium/enzymology , Oxygen ConsumptionABSTRACT
A trifluoroleucine-resistant mutant of yeast has been isolated that exhibits reduced incorporation of the analogue into protein (15%) of that in the wild type. In the mutant, uptake of the analogue and leucine into the expandable (water-extractable) pool is enhanced, passage from the expandable to the conversion (nonwater-, ethanol-extractable) pool is unaffected, and endogenous synthesis of leucine is normally regulated. Although the leucyl transfer ribonucluic acid (tRNA) synthetase appears normal, and the tRNA(leu) has wild-type acceptor activities in vitro and in vivo, the level of the mutant trifluoroleucyl tRNA pool is only 2 to 3% of that in the wild type. The data support the idea of a mutation affecting passage between the conversion pool and the site of charging of the analogue. The mutation is dominant and exhibits pleiotropic effects: the first leucine biosynthetic enzyme appears nonrepressible, and the leucine, valine, and tyrosine uptake systems are constitutively elevated (three- to fourfold) in the absence of exogenous amino acids.
