The biochemical basis for sulfite accumulation by sulfate-using revertants of Salmonella pullorum was determined. All of the sulfate-using mutants isolated from wild-type S. pullorum accumulated sulfite when grown at 37 but not at 25 C. The specific activity of reduced nicotinamide adenine dinucleotide (NADPH)-dependent sulfite reductase (H2S-NADP oxidoreductase, EC 1.8.1.2) and of reduced meth...

In an assay measuring virus-directed RNA synthesis, infection of BHK cells by a standard test dose of vesicular stomatitis virus (VSV) was inhibited by ultraviolet light-irradiated wt VSV and by ts 045, one of a number of thermolabile, temperature-sensitive G protein mutants of VSV. After heat treatment for 1 h at 45 degrees C, the thermolabile mutants were no longer able to inhibit the VSV inf...

W e have isolated temperature resistant revertants from temperature sensitive E. coli strains containing either a thermolabile g lutaminyltRNA synthetase or leucyl-tRNA synthetase. Among the revertants which still contained the thermolabile leucyl-tRNA shynthetase w e found two classes of regulatory mutants (leuX and leuY) which have elevated levels of this enzyme. T h e leuX mutation specifies...

Temperature sensitivity of the regulatory protein coded by nifA prevents the organism from utilizing N2 at 37 degrees C. The purpling of 6-cyanopurine, a function of nifA expression, also is thermolabile.