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PubMed1963

ELECTROPHORETIC STUDY OF THE INTERACTION OF RADIOACTIVE POLIOVIRUS WITH COMPONENTS OF CULTURED CELLS.

Thorne, H. V. (University of Minnesota, Minneapolis). Electrophoretic study of the interaction of radioactive poliovirus with components of cultured cells. J. Bacteriol. 85:1247-1255. 1963.-The interaction of P(32)-labeled poliovirus with the postnuclear fraction of HeLa cell homogenates was first examined using radioactivity to quantitate the reaction. The effects of virus and debris concentration, suspending medium, temperature, and time on the reaction were determined. Binding was independent of salt concentration up to 1.0 m and unaffected by calcium and magnesium ions at 10(-3)m. The postnuclear particulate components of homogenates of mammalian cells in culture were examined by sucrose gradient zone electrophoresis at pH 7.2 with a simple apparatus which permitted several simultaneous analyses. The distributions of components for different cell types were distinct and appeared to be influenced by conditions of culture. Addition of radioactive poliovirus to the homogenate before analysis was used to identify components with virus-binding activity. Activity of HeLa and human esophageal epithelium cell homogenates was found mainly in membranous fractions of relatively low electrophoretic mobility. Components with a broader spread of mobility were moderately active in cultured human amnion, but uncultured amnion had almost undetectable virus-binding activity and a distinct distribution of components. Rat heart cells and L cells did not bind poliovirus, but binding components were present in both ERK-1 and CRE rabbit lines.

Animals↗
PubMed1963

ACCUMULATION OF INORGANIC POLYPHOSPHATE IN AEROBACTER AEROGENES. I. RELATIONSHIP TO GROWTH AND NUCLEIC ACID SYNTHESIS.

Harold, F. M. (National Jewish Hospital, Denver, Colo.). Accumulation of inorganic polyphosphate in Aerobacter aerogenes. I. Relationship to growth and nucleic acid synthesis. J. Bacteriol. 86:216-221. 1963.-Growing cells of Aerobacter aerogenes contain traces of inorganic polyphosphate, but large amounts often accumulate when growth ceases as the result of a nutritional deficiency. The reciprocal relationship between growth and polyphosphate accumulation was traced to competition between nucleic acid synthesis and polyphosphate for intracellular phosphorus. Polyphosphate accumulated only after nucleic acid synthesis had ceased. Resumption of nucleic acid synthesis (with or without concurrent cell growth) induced rapid degradation of the polyphosphate with transfer of the phosphorus to ribonucleic acid (RNA). At the same time, incorporation of P(32) into polyphosphate was reduced, though not abolished. Competition for adenosine triphosphate may be part of the explanation. In addition, it appears that polyphosphate degradation is accelerated under conditions which permit rapid nucleic acid synthesis, the phosphorus released being trapped in RNA.

DNA↗
PubMed1963

ACCUMULATION OF INORGANIC POLYPHOSPHATE IN AEROBACTER AEROGENES. II. ENVIRONMENTAL CONTROL AND THE ROLE OF SULFUR COMPOUNDS.

Harold, F. M. (National Jewish Hospital, Denver, Colo.) and Susan Sylvan. Accumulation of inorganic polyphosphate in Aerobacter aerogenes. II. Environmental control and the role of sulfur compounds. J. Bacteriol. 86:222-231. 1963.-The accumulation of inorganic polyphosphate in Aerobacter aerogenes was shown to be a function of the growth medium. In low-phosphate medium, polyphosphate accumulated whenever nucleic acid synthesis ceased due to a nutritional deficiency, regardless of its nature. In high-phosphate medium polyphosphate accumulation was induced only by sulfur starvation. Polyphosphate accumulation could thus be induced or suppressed at will by manipulation of the sulfur and phosphorus content of the medium. The specific requirement for sulfur starvation was traced to the presence of an intracellular inhibitor of polyphosphate accumulation. This was depleted during sulfur starvation and replenished when sulfate was restored. The inhibitor was identified as oxidized glutathione or a closely related compound. Suppression of polyphosphate accumulation required the simultaneous presence of a high exogenous phosphate concentration and a high intracellular glutathione level. Suppression of polyphosphate accumulation resulted in a constant polyphosphate level, due to a steady state of polyphosphate synthesis and degradation. The former continued at half the original rate while the latter was sharply accelerated. The synthetic and degradative phases of polyphosphate metabolism could be completely dissociated by inhibitors of energy generation. It is proposed that the primary effect of glutathione plus phosphate is the stimulation of polyphosphate degradation. Polyphosphate synthesis appears to be a general consequence of the inhibition of nucleic acid synthesis, but net accumulation may be obscured by concurrent degradation.

Culture Media↗
PubMed1963

FAILURE OF ARSENATE TO UNCOUPLE THE PHOSPHOTRANSACETYLASE SYSTEM IN CLOSTRIDIUM ACIDIURICI.

Sagers, Richard D. (Brigham Young University, Provo, Utah), Moshe Benziman, and Sigrid M. Klein. Failure of arsenate to uncouple the phosphotransacetylase system in Clostridium acidiurici. J. Bacteriol. 86:978-984. 1963.-The conversion of pyruvate to acetyl phosphate by extracts of Clostridium acidiurici required coenzyme A (CoA), an electron-carrier system (ferredoxin and nicotinamide adenine dinucleotide), and a divalent metal. Other cofactors may be involved but are not presently defined. The metal activates the system transferring acetyl units between CoA and phosphate. Acetyl CoA could be generated from pyruvate or from acetyl phosphate, but in both cases arsenate failed to uncouple the high-energy acyl compounds. The rate of acetyl transfer between acetyl phosphate and CoA was markedly decreased by 0.005 m arsenate, but the generation of acetyl CoA from pyruvate was essentially unaffected until the arsenate concentration exceeded 0.02 m. Close agreement was observed between the amount of pyruvate utilized and the amount of acetyl phosphate formed, both in the presence and absence of arsenate. The CoA-dependent exchange of P(32)O(4) ( identical with) with acetyl phosphate proceeded at a rate approximately one-eightieth of the rate of acetylation of CoA, indicating an equilibrium value for the phosphotransacetylase reaction similar to that observed for Clostridium kluyveri. The failure of arsenate to uncouple the C. acidiurici enzyme may indicate a high degree of specificity in relation to the acetyl unit acceptor, giving preference to phosphate over arsenate.

Acetyl Coenzyme A↗