Skip to ContentSkip to Navigation
About us Latest news News News articles

Beyond bottlenecks in membrane protein production

15 October 2010

PhD ceremony: Mr. R.K.R. Marreddy, 13.15 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Beyond bottlenecks in membrane protein production

Promotor(s): prof. B. Poolman

Faculty: Mathematics and Natural Sciences

 

The structural and functional analysis of complex multi-domain (membrane) proteins is hampered in large part due to problems associated with their overproduction in a functional state. The bacterium Lactococcus lactis is a suitable host for overexpression of membrane proteins. Although many pro- and eukaryotic proteins are expressed well in L. lactis, other proteins are difficult to (over)produce. In many cases L. lactis and other expression hosts are grown in complex media as proteins are expressed best under those conditions. However, for the incorporation into proteins of specific amino acid analogues, which is advantageous for various biophysical studies, one requires a chemically defined medium. We have used a comparative proteomeics approach to determine why proteins are produced at higher levels in complex than in synthetic media. We could show that in the synthetic media the intracellular levels of branched-chain amino acids become limiting for biosynthesis, and, importantly, we could overcome this limitation either by overexpressing the corresponding amino acid transport protein or providing to cell with an alternative path for amino acid accumulation (e.g. via uptake of peptides). Subsequentely, we determined why certain membrane proteins are not well expressed while others do. Here, the physiological response of the cell was studied by a combined proteomics and transcriptomics approach. The overproduction of membrane proteins in L. lactis invoked a general stress response (upregulation of various chaperones), a severe metabolic burden and a specific cell envelope stress response. With this basic knowledge of the physiological response of the cells, it should be possible engineer to engineert the expression hosts for improved membrane protein production. Initial successes in improving the biosynthesis of medically-important membrane proteins have been obtained.

 

 

Last modified:13 March 2020 01.16 a.m.
Share this Facebook LinkedIn
View this page in: Nederlands

More news

  • 13 June 2025

    Team 'Lord of the Roads' second at RDW Self Driving Challenge

    The University of the North team 'Lord of the Roads', in which students from educational institutions Noorderpoort, Hanzehogeschool and the University of Groningen collaborated, came second in the RDW Self Driving Challenge (SDC). The team competed...

  • 12 June 2025

    Those most affected by modern agriculture

    Farmers only grow a limited number of crops these days, which has significant consequences for the animals that live there. Raymond Klaassen researches what adjustments farmers could make to improve the conditions for the species most affected by...

  • 06 June 2025

    India-Netherlands Hydrogen Valley Fellowship Programme announced

    To coincide with World Environment Day, 5 June 2025, the Indian Department of Science and Technology and the University of Groningen yesterday announced a Hydrogen Valley Fellowship Programme Partnership, allowing talented Indian scholars working on...