Skip to comments.Maize cells produce enzyme-replacement drug: A genetic tweak keeps problematic plant sugars...
Posted on 09/19/2012 11:35:49 PM PDT by neverdem
A genetic tweak keeps problematic plant sugars off therapeutic proteins.
Growing crops is simpler and cheaper than culturing mammalian cells, which can harbour human pathogens and must be kept at precise temperatures and fed particular nutrients. But culturing mammalian cells is currently the only way to make some complex protein drugs.
For example, the rare lysosomal storage disease mucopolysaccharidosis I is treated using enzyme-replacement therapy. The enzymes must be made in cells, and the high production costs mean that the drugs can cost hundreds of thousands of dollars a year. So Allison Kermode, a plant biologist at Simon Fraser University in Burnaby, Canada, whose husband works with people who have lysosomal storage disorders, decided to develop a way to manufacture the necessary enzymes in maize (corn).
When human proteins such as enzymes are expressed in plant cells, they are usually decorated with plant-specific sugar molecules, which could prompt a dangerous immune reaction if injected into patients. But today in Nature Communications1, Kermode and her colleagues describe how they avoided these modifications.
The team tweaked the protein-producing genes, not to alter the sequence of the human protein, but to ensure that, once made, the proteins would not be moved through the cell's Golgi complex, a structure where the problematic sugars are added. The engineered maize seeds produced proteins decorated with sugars that could be converted to human forms.
Richard Pattison, a cell biologist at the Boyce Thompson Institute for Plant Science in Ithaca, New York, calls the approach very elegant. Most attempts to solve the sugar problem require mutating the protein, which could disrupt its function, or engineering plants to modify proteins differently a time-consuming approach that often does not work...
(Excerpt) Read more at nature.com ...
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