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ETH Researchers Open New Perspectives for Biotechnology

November 28, 2002

Metabolic and biochemical reactions are basically the same in all living beings, or at least comparable. The genetic codes of all living beings, that is to say of bacteria, plants, fungii and animals, are made up of the same set of building blocks. Human genes are therefore correctly translated into the corresponding proteins even by bacteria. The features that both bacteria and higher forms of life (so-called eukaryotes) have in common end, however, with the synthesis of «raw proteins» since unlike bacteria, eukaryotes process many of their raw proteins further. This additional processing is known in technical jargon as «post-translation modification». What this means is that the raw proteins are cut to size or biochemically modified by the cells. The so-called N-linked bonding of proteins with sugar building blocks is particularly frequent. And it was precisely this that bacteria could not do, or so it was thought until a short while ago.

Bacteria, too, Can Modify Proteins

To the surprise of many scientists, it became evident during the past years that some species of bacteria are also capable to modify raw proteins. The ETH researchers have been able, together with their English colleagues, to demonstrate that Campylobacter bacteria – like higher forms of life – can provide proteins with N-linked sugars. Campylobacter bacteria are, however, pathogens that cause diarrhoea and therefore difficult to use for research and biotechnological purposes; microbiologists and biotechnologists prefer to use Escherichia coli (E. coli). The researchers have now managed to transfer the property of post-translation modification, that is to say the attachment of sugar residues to proteins, from Campylobacter to E. coli. These E. coli cells can produce proteins with N-linked sugars.

Cheaper Ways of Manufacturing Medicines

In order to investigate the way in which medicinally active proteins work or even to use them as drugs, large quantities if them are needed. Until now proteins, that are only functional after post-translation modification, were produced with the help of animal, human or yeast cells. Bacteria are, however, considerably better and less expensive producers, the products would be simpler and cheaper to make. The work of the ETH researchers now opens up the prospect of being able to produce proteins, for example many hormones or immunologically active substances, at lower costs. This will benefit both basic research in the fields of medicine and biology and many biotech companies. But much intensive research will be required before this can become reality.

ETH Zuerich