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Principal Investigator

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P4  Christine Ziegler
Professorin

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Institute of Biophysics and Biophysical Chemistry, 
University of Regensburg
95053 Regensburg

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Former member of the

Department of Structural Biology
Max Planck Institute of Biophysics
60438 Frankfurt am Main, Germany


P4 Dynamic molecular description of transport regulation in BetP


The molecular understanding of secondary transport, in particular how transport activity is regulated, is one of the cutting-edge questions in biological science. The osmoregulated betaine symporter BetP, one of the best-characterized regulated carriers, responds to osmotically driven changes in the membrane and in cytoplasmic K+-concentration. We have solved seven X-ray structures of tri-meric BetP in different conformational states under active and inactive conditions. In combination with our functional data, we obtained first insights into a molecular mechanism of regulated transport in BetP. For the future, we aim for a complete and dynamic description of osmoregulation in BetP in the sense of a molecular movie by combining X-ray and electron crystallography with functional measurements, EPR spectroscopy and bioinformatics. Firstly we will focus on solving the last two missing states of the alternating-access cycle of BetP. Secondly we will investigate by crystallog-raphy and PELDOR how alternating-access in BetP is affected by a ternary regulatory interaction network of the terminal domains and anionic lipids during K+-activation. Thirdly we will exploit our knowledge on BetP to understand transport of the medically important osmolytes ectoine and tau-rine. In addition, we will study structure and function of putative ancestor proteins to investigate the evolutionary link between unrelated osmolyte transporter families. 

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Rigid body fitting of the X-ray structure of BetP to 3.3Å resolution to the 3D map of BetP determined by electron-crystallography to 8Å from 2D crystals.
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Publications

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Spindler P, Waclawska I, Endeward B, Plackmeyer J, Ziegler C, Prisner T* (2015) Carr-Purcell pulsed electron double resonance with shaped inversion pulses. J Phys Chem 6, 4331-5. 

Schweikhard ES, Burckhardt BC, Joos F, Fenollar-Ferrer C, Forrest LR, Kempson SA, Ziegler C* (2015) Role of N-glycosylation in renal betaine transport. Biochem J 470, 169-79. 

Waclawska I, Ziegler C* (2015) Regulatory role of charged clusters in the N-terminal domain of BetP from Corynebacterium glutamicum. Biol Chem 396, 1117-26. 

Koshy C, Ziegler C (2015) Structural insights into functional lipid-protein interactions in secondary transporters. Biochim Biophys Acta 1850, 476-487. 

Keller R, Ziegler C, Schneider D (2014) When two turn into one: evolution of membrane transporters from half modules. Biol Chem 395, 1379-1388.

Perez C, Faust B, Mehdipour AR, Francesconi KA, Forrest LR*, Ziegler C* (2014) Substrate-bound outward-open state of the betaine transporter BetP provides insights into Na+ coupling. Nat Commun 155, 4231. 

 

Schweikhard ES, Kempson SA, Ziegler C, Burckhardt BC (2014) Mutation of a single threonine in the cytoplasmic NH2 terminus disrupts trafficking of renal betaine-GABA transporter 1 during hypertonic stress. Am J Physiol Renal Physiol 307, F107-115. 

 

Sand M, Stahl J, Waclawska I, Ziegler C, Averhoff B* (2014) Identification of an osmo-dependent and an osmo-independent choline transporter in Acinetobacter baylyi: implications in osmostress protection and metabolic adaptation. Environ Microbiol 16, 1490-1502. 

 

Koshy C, Schweikhard ES, Gärtner RM, Perez C, Yildiz O, Ziegler C* (2013) Structural evidence for functional lipid interactions in the betaine transporter BetP. EMBO J 32, 3096-3105. 

 

Perez C, Ziegler C* (2013) Mechanistic aspects of sodium-binding sites in LeuT-like fold symporters. Biol Chem 394, 641-648. 

 

Korkmaz F, Ressl S, Ziegler C*, Mäntele W* (2013) K(+)-induced conformational changes in the trimeric betaine transporter BetP monitored by ATR-FTIR spectroscopy. Biochim Biophys Acta 1828, 1181-1191. 

 

Schweikhard ES, Ziegler CM (2012) Amino acid secondary transporters: toward a common transport mechanism. Curr Top Membr 70, 1-28. 

 

Khafizov K, Perez C, Kosh C, Quick M, Fendler K, Ziegler C*, Forrest LR* (2012) Investigation of the sodium-binding sites in the sodium-coupled betaine transporter BetP. Proc Natl Acad Sci USA 109, E3035-3044. 

 

Perez C, Koshy C, Yildiz O, Ziegler C (2012) Alternating-access mechanism in conformationally asymmetric trimers of the betaine transporter BetP. Nature 490, 126-310.

* corresponding authors 

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Collaborations

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Kühlbrandt (P1), Michel (P3), Prisner (P7), Fendler/Bamberg (P10), Schäfer (P19)