This study of the relationship between heterologous protein production and bacterial growth has shown that foreign protein can account for as much as 30% of the total cell protein without the specific growth rate being affected. Higher levels of foreign protein production are achieved at lower growth rates. Foreign protein is synthesised without any increase in ribosome number or ribosome activity occurring in the recombinant cells relative to their parent strain, i.e. the capacity of parental and recombinant cells to synthesise protein is the same. These observations are explained in terms of a model in which Escherichia coli proteins are be divided into two types. Type I proteins are involved in the processes of transcription and translation. Type 2 proteins are those which serve other purposes. The model suggests that the synthesis of type 2 proteins will be decreased in order to accommodate foreign protein production. This implies that some Escherichia coli proteins are overproduced relative to the amount of that protein that is essential to the cell to maintain growth. Two dimensional electrophoresis showed that there was a decrease in some host cell protein levels between parental and recombinant cells. An increase in the levels of molecular chaperone proteins in recombinant cells grown under some conditions was observed. These data are explained in terms of our current understanding of the regulation of molecular chaperone production. The data obtained are discussed in relation to our current understanding of the growth of bacteria and the reported effects of high levels of foreign protein production on bacterial physiology.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:265539 |
| Date | January 1998 |
| Creators | Broadhead, Richard Ian |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU104201 |
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