@article{MietrachSchlosserGeibel2019, author = {Mietrach, Nicole and Schlosser, Andreas and Geibel, Sebastian}, title = {An extracellular domain of the EsaA membrane component of the type VIIb secretion system: expression, purification and crystallization}, series = {Acta Crystallographica Section F}, volume = {75}, journal = {Acta Crystallographica Section F}, number = {12}, doi = {10.1107/S2053230X1901495X}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213681}, pages = {725-730}, year = {2019}, abstract = {The membrane protein EsaA is a conserved component of the type VIIb secretion system. Limited proteolysis of purified EsaA from Staphylococcus aureus USA300 identified a stable 48 kDa fragment, which was mapped by fingerprint mass spectrometry to an uncharacterized extracellular segment of EsaA. Analysis by circular dichroism spectroscopy showed that this fragment folds into a single stable domain made of mostly α-helices with a melting point of 34.5°C. Size-exclusion chromatography combined with multi-angle light scattering indicated the formation of a dimer of the purified extracellular domain. Octahedral crystals were grown in 0.2 M ammonium citrate tribasic pH 7.0, 16\% PEG 3350 using the hanging-drop vapor-diffusion method. Diffraction data were analyzed to 4.0 {\AA} resolution, showing that the crystals belonged to the enantiomorphic tetragonal space groups P41212 or P43212, with unit-cell parameters a = 197.5, b = 197.5, c = 368.3 {\AA}, α = β = γ = 90°.}, language = {en} }