Regensburg 2004 – scientific programme
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SYLS: Life Sciences on the Nanometer Scale - Physics Meets Biology
SYLS 3: Symposium "Life Sciences on the Nanometer Scale - Physics Meets Biology"
SYLS 3.43: Poster
Wednesday, March 10, 2004, 16:00–18:30, B
Investigating structure and function of single citrate transport proteins — •Michael Prummer1, Horst Vogel1, Beate Sick2, Alois Renn3, Urs P. Wild3, Christopher N. Kästner4, and Peter Dimroth4 — 1Institute of Biomolecular Sciences, EPFL, CH-1015 Lausanne — 2DNA-Array Facility, University of Lausanne, CH-1015 Lausanne — 3Physical Chemistry Laboratory, ETH-Hönggerberg, CH-8093 Zürich — 4Institute of Microbiology, ETH-Zentrum, CH-8092 Zürich
We have utilized fluorescence quenching to study functional conformational changes in single membrane transport proteins upon substrate binding. The fluorescence of a fluorophore, specifically attached to the citrate carrier CitS, was completely quenched upon addition of citrate, but not DL-isocitrate. After exclusion of other possible reasons we attribute the quenching to conformational changes of CitS in the citrate transport cycle. Many membrane proteins are thought to obtain their functional state upon dimerization. To test the hypothesis in a very direct way, whether or not also CitS occurs as a dimer, we conducted a dual-color colocalization experiment and found strong evidence for a homo-dimeric arrangement of CitS.