Coupling protein dynamics to membrane morphology.
EMSL Project ID
34908
Abstract
Membranes are fluid, plastic and adaptable. But how do they transform themselves from fulfilling one function to taking on a task that may be completely new? What are the underlying dynamics that permit such changes at the molecular level? These are the questions we wish to address in this application.To answer these questions we have chosen Rhodobacter sphaeroides, which possesses highly adaptable membranes. For example, in air its membranes are indistinguishable from regular plasma membrane. If oxygen is removed the membrane begins to invaginate, pigment-protein complexes are synthesized and the organism develops photosynthetic membranes (ICM). Thus, membrane dynamics permit a complete lifestyle change. In addition, if the cells are growing in high light and the light intensity decreases, the membrane expands and new components are added to capture more light. On the other hand, if the light intensity increases, the membrane is downsized as needed.
We have the ability to isolate the ICM in essentially pure form. Therefore, we can follow over time the protein dynamics that are involved as the membrane changes between forms. In this application we have chosen to examine the ICM changes that occur when this organism is transitioned between the following two light environments; a shift from low light to high light, and a shift from high light to low light. In these cases we want to determine if "old" membrane remains unaltered and is diluted out with time, while "new" membrane is added alongside. Or, does "old" membrane become modified with new proteins so that it becomes "new" membrane? Once this pattern is known we can examine the underlying cause. We also wish to examine what happens when oxygen is added to a photosynthetic culture. Does the ICM get converted to regular plasma membrane, or does the ICM get diluted out over successive rounds of cell division as new aerobic membrane is synthesized?
In order to address these questions we wish to grow cells under one condition then shift them to another condition. At time points post shift we will collect samples and analyze them with a number of different technologies including GFP-tagging, electron microscopy and gene-chip technology,. However, our main interest and the purpose of this application is to request assistance from Drs. Mary Lipton, Steven Callister and co-workers for their expertise and the use of accurate mass and time (AMT) mass spectrometry. We have had very fruitful collaborations in the past and we feel that the time is now ripe to put this technology to work to lay out a fate map for membrane remodeling. Such a map would be of fundamental interest to the biological community and would lay a foundation for determining if similar maps have been conserved across microbial evolution.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2009-10-08
End Date
2010-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members