The ribosomes of Vibrio costicola were stable over a wide range of salt concentrations. Sucrose gradient profiles of ribosomes from cells grown in different salt concentrations and isolated in various salt concentrations were similar. The sedimentation coefficients of the ribosomal particles were 64, 48, and 28 S for the monosome, large subunit, and small subunit, respectively. These values were not altered by the NaCl concentration of the growth medium nor by the salt concentration of the isolation buffer. There was, however, slight evidence that higher salt concentrations were removing some of the ribosomal proteins. The total ribosomal proteins were found to be more acidic (B/A = 1.08) than the total ribosomal proteins of E. coli (B/A = 1.58) but less acidic than the total ribosomal proteins of H. cutirubrum (B/A = 0.69). The relative acidity of the total ribosomal proteins was not changed by the NaCl concentration the growth medium. Two ribosomal proteins equivalent to the E. coli S1 and L7/12 were purified and the partial amino acid sequence of the latter was determined. The V. costicola protein was 79% homologous with the E. coli protein and 74% homologous with an equivalent protein from the unclassified moderate halophile, H.x. The average hydrophobicity of the V. costicola total and purified ribosomal proteins were not significantly different than those of E. coli. An in vitro protein synthesizing system was developed for V. costicola. The in vitro system was energy dependent and sensitive to inhibitors of protein synthesis. The poly-uridylic acid dependent system incorporated phenylalanine into oligophenylalanines. The in vitro system directed by poly-U had a salt optimum of 0.15 M with greater activity in NH4Cl than KCl which had greater activity than NaCl. The magnesium optimum was approximately 18 mM. The in vitro system directed by "endogenous" messenger had similar salt response as the poly-U system except that NaCl was inhibitory at all concentrations. Increasing the salt concentration above the optimum increased the misreading of the poly-U message. The in vitro protein synthesizing system was stable for at least 8 hours in 1.0 M NaCl, KCl, or NH4Cl. The ribosomes and protein synthesizing system demonstrated considerable salt stability. The low salt optimum of the protein synthesis system and previously studied V. costicola enzymes and the effects of salts on misreading of poly-U suggest that the distribution of ions measured as intracellular may not be uniform throughout the cell. The envelope of the cell may bind large amounts of these ions leaving the cytoplasm with a relatively low "free" ion concentration.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/10606 |
| Date | January 1977 |
| Creators | Wydro, Robert M. |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 175 p. |
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