Using Rhodobacter Bacteria to Express Membrane Proteins (ANL-IN-99-089)
Cell membranes serve as the biological structure through which an organism interacts with its environment. Making up the cell membrane are numerous proteins responsible for many processes including nutrient uptake, excreting metabolic waste, and responding to external stimuli.
Because of their unique properties, membrane proteins are difficult to isolate and purify. Most existing systems for expressing heterologous membrane proteins are either costly or suffer from various disadvantages. Scientists at Argonne National Laboratory have devised a proprietary method for expressing and purifying hetrologous membrane proteins by using photosynthetic bacteria (Rhodobacter).Description
Membrane proteins play a mediating role between external stimuli and the cell’s internal metabolism. For this reason, the majority of drug targets are membrane proteins. However, membrane proteins are hydrophobic—that is, they are insoluble and highly unstable in the aqueous environments typically used to produce and characterize soluble proteins. Thus, it is difficult to purify them in quantities and at a level of quality sufficient for conducting structural or functional studies. That is why—compared to about 15,000 unique structures known for representatives of soluble protein families—researchers have determined the unique structures of only about 200 membrane proteins.
Only a few systems enable the expression of heterologous membrane proteins, and most present disadvantages to researchers. For example, eukaryotic expression systems are costly, and a system that uses the E. coli bacterium can cause host toxicity or produce insoluble aggregates. However, a unique system invented by Argonne scientists Philip Laible and Deborah Hanson obtains reasonable yields of functional membrane protein. Their proprietary method expresses heterologous membrane proteins through the use of photosynthetic Rhodobacter bacteria.
Rhodobacter cells produce extremely large amounts of intracellular membrane when cultured under certain conditions. Synthesis of foreign (or native) membrane proteins and this intracellular membrane can be coordinated in these bacteria. After culture, the functional membrane protein can be purified easily by using standard protocols, such as affinity chromatography.Benefits
- Lower production costs
- Ease of purification
- Permits high yields (from 0.5 mg/L to up to 20 mg/L)
- Allows the simultaneous production and sequestration of heterologous membrane proteins (with no toxicity to host).
This system has strong application for both the pharmaceuticals and biotechnology industries. Additionally, as biologics become more mainstream, large quantities of active membrane proteins will be required for regulatory testing.Patents and Patent Applications
|Title and Abstract||
Methods and constructs for expression of foreign proteins in photosynthetic organisms
A method for expressing and purifying foreign proteins in photosynthetic organisms comprising the simultaneous expression of both the heterologous protein and a means for compartmentalizing or sequestering of the protein.
|Argonne National Laboratory||10/15/2002
|Technology ID||Development Stage||Availability||Published||Last Updated|
|ANL-IN-99-089||Production - Ready to transfer to industry for commercial development||Available||02/07/2012||02/07/2012|