@article{KoelschRadonGolubetal.2020, author = {K{\"o}lsch, Adrian and Radon, C. and Golub, M. and Baumert, A. and B{\"u}rger, J{\"o}rg and Mielke, Thorsten and Lisdat, Fred and Feoktystov, A. and Pieper, J. and Zouni, Athina and Wendler, P.}, title = {Current limits of structural biology: The transient interaction between cytochrome c6 and photosystem I}, series = {Current Research in Structural Biology}, volume = {2}, journal = {Current Research in Structural Biology}, issn = {2665-928X}, doi = {10.1016/j.crstbi.2020.08.003}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-13628}, pages = {171 -- 179}, year = {2020}, abstract = {Trimeric photosystem I from the cyanobacterium Thermosynechococcus elongatus (TePSI) is an intrinsic membrane protein, which converts solar energy into electrical energy by oxidizing the soluble redox mediator cytochrome c6 (Cyt c6) and reducing ferredoxin. Here, we use cryo-electron microscopy and small angle neutron scattering (SANS) to characterize the transient binding of Cyt c6 to TePSI. The structure of TePSI cross-linked to Cyt c6 was solved at a resolution of 2.9 {\AA} and shows additional cofactors as well as side chain density for 84\% of the peptide chain of subunit PsaK, revealing a hydrophobic, membrane intrinsic loop that enables binding of associated proteins. Due to the poor binding specificity, Cyt c6 could not be localized with certainty in our cryo-EM analysis. SANS measurements confirm that Cyt c6 does not bind to TePSI at protein concentrations comparable to those for cross-linking. However, SANS data indicate a complex formation between TePSI and the non-native mitochondrial cytochrome from horse heart (Cyt cHH). Our study pinpoints the difficulty of identifying very small binding partners (less than 5\% of the overall size) in EM structures when binding affinities are poor. We relate our results to well resolved co-structures with known binding affinities and recommend confirmatory methods for complexes with KM values higher than 20 μM.}, language = {en} } @misc{StiegerFeifelLoksteinetal.2018, author = {Stieger, Kai Ralf and Feifel, Sven Christian and Lokstein, Heiko and Hejazi, Mahdi and Zouni, Athina and Lisdat, Fred}, title = {Biohybride Architekturen f{\"u}r eine effiziente Umwandlung von Licht in elektrische Energie durch Integration von Photosystem I in skalierbare mesopor{\"o}se 3D Elektroden}, series = {Wissenschaftliche Beitr{\"a}ge 2018}, volume = {22}, journal = {Wissenschaftliche Beitr{\"a}ge 2018}, issn = {0949-8214}, doi = {10.15771/0949-8214_2018_2}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:526-opus4-10220}, pages = {17 -- 24}, year = {2018}, abstract = {Die Kombination von fortschrittlichen Materialien und kontrolliertem Oberfl{\"a}chendesign mit komplexen Proteinen aus der nat{\"u}rlichen Photosynthese ist derzeit eines der Hauptthemen bei der Entwicklung von Biohybridsystemen und Biophotovoltaik. In dieser Studie werden transparente makropor{\"o}se Indium-Zinn-Oxid-(μITO-) Elektroden mit dem trimeren Superkomplex Photosystem I (PSI) aus dem Cyanobakterium Thermosynechococcus elongatus sowie dem kleinen Redoxprotein Cytochrom c (Cyt c) kombiniert, um neuartige und effiziente biohybride Photokathoden herzustellen. Mit diesen bis zu 40 μm hohen 3D-Strukturen k{\"o}nnen beide Proteine in einer ann{\"a}hernden Monolage abgeschieden werden und die elektrische Kommunikation mit der Elektrode kann erzielt werden. Der generierte Photostrom folgt dabei linear der kontrollierbaren Schichtdicke der μITO-Elektrode, wobei Stromdichten von bis zu 150 μA cm -2 erhalten werden. Eine effiziente elektrische Kopplung der Proteine kann durch die hohe interne Quanteneffizienz von 30 \% gezeigt werden.}, language = {de} }