title: Regulation of two aspartokinases in Bacillus subtilis.
abstract: When grown on minimal glucose medium, transformable Bacillus subtilis strains contained two distinct aspartokinases (ATP:l-aspartate 4-phosphotransferase, EC 2.7.2.4). One of these enzymes was inhibited by l-lysine (Lys), whereas the other was insensitive to inhibition but was activated by l-leucine. None of the other amino acids tested had any effect, and the addition of l-threonine did not enhance the inhibition by Lys, in contrast to the concerted inhibition observed for other bacilli. At the end of exponential growth, the Lys-sensitive aspartokinase activity decreased, whereas the Lys-insensitive activity remained relatively constant throughout the stationary phase. The two activities were separated by (NH(4))(2)SO(4) fractionation and Sephadex G-200 chromatography. Growth in the presence of Lys reduced the specific activity of aspartokinase by about 50% and eliminated the inhibition by Lys. In extracts of these cells, only Lys-insensitive activity was found upon (NH(4))(2)SO(4) fractionation and Sephadex G-200 chromatography. Lys apparently repressed the synthesis of the Lys-sensitive enzyme.
mesh_terms: D000645:Ammonium Sulfate; D001224:Aspartic Acid; D001412:Bacillus subtilis / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D002474:Cell-Free System; D011232:Chemical Precipitation; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003470:Culture Media; D004789:Enzyme Activation; D004794:Enzyme Repression; D005947:Glucose / Q000378:metabolism; D006877:Hydroxamic Acids / Q000096:biosynthesis; D007930:Leucine / Q000494:pharmacology; D008239:Lysine / Q000494:pharmacology; D010759:Phosphorus Isotopes; D010770:Phosphotransferases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D013171:Spores, Bacterial / Q000254:growth & development; D013237:Stereoisomerism; D013912:Threonine / Q000494:pharmacology; D013997:Time Factors; D014170:Transformation, Genetic
chemical_list: D003470:Culture Media; D006877:Hydroxamic Acids; D010759:Phosphorus Isotopes; D013912:Threonine; D001224:Aspartic Acid; D010770:Phosphotransferases; D007930:Leucine; D005947:Glucose; D008239:Lysine; D000645:Ammonium Sulfate