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K C Zoon

Publications and source records attributed to K C Zoon.

60 records · Page 4Linked to original sources

Synthesis of envelope polypeptides by Haemophilus influenzae during development of competence for genetic transformation.

Six polypeptides with apparent molecular weights of 95,000, 90,000, 80,000, 67,000, 64,000, and 43,000 were found to be characteristic of the cell envelopes of competent Haemophilus influenzae, and were synthesized entirely during the period of competence development. Two polypeptides with apparent molecular weights of 58,500 and 40,500 were synthesized during growth as well as during competence development, but were only associated with the envelope fraction of cells that had developed competence. The kinetics of synthesis of the competence-related envelope polypeptides showed a lag period of approximately 20 min. The observation of this lag period raises the question as to whether some of these competence-related polypeptides might be involved in the process of deoxyribonucleic acid uptake, since the development of this property also exhibits a sigmoid time course during competence development.

Bacterial Proteins↗

Constitution of the cell envelope of Haemophilus influenzae in relation to competence for genetic transformation.

Cell envelopes of Haemophilus influenzae have been prepared by breakage in a French pressure cell followed by differential centrifugation. The envelope fraction may be resolved into an inner-membrane (light) and an outer-membrane (heavy) fraction on density gradients. Envelopes from competent cells possess elevated levels of lipopolysaccharide with a composition different from that of log-phase cell envelopes. Three apparently new polypeptides have been observed in envelopes from competent cells by gel electrophoresis in sodium dodecyl sulfate; additional quantitative alterations in the profiles of membrane polypeptides also company the development of the capacity to transport deoxyribonucleic acid. Most of the polypeptide changes are confined to the outer membrane; one new polypeptide is associated with the inner cytoplasmic membrane of competent cells. Protein synthesis during competence developement is rquired for the change in lipopolysaccharides and in the envelope polypeptides to occur.

Bacterial Proteins↗

Specificity in deoxyribonucleic acid uptake by transformable Haemophilus influenzae.

Cells of Haemophilus influenzae strain Rd competent for genetic transformation irreversibly bound approximately five molecular fragments of H. influenzae deoxyribonucleic acid (DNA) per cell; under identical conditions, DNA derived from Escherichia coli B was not taken up (<1 molecule per 50 cells). Similarly, DNA from Xenopus laevis was not taken up by competent H. influenzae. Of the heterologous DNAs tested, only DNA from H. parainfluenzae interfered with the uptake of H. influenzae DNA, as judged by competition experiments employing either DNA binding or genetic transformation as the test system. The extracellular heterologous DNA did not suffer either single- or double-strand breakage upon exposure to competent H. influenzae.

Animals↗