TY  - JOUR
A1  - Mietrach, Nicole
A1  - Schlosser, Andreas
A1  - Geibel, Sebastian
T1  - An extracellular domain of the EsaA membrane component of the type VIIb secretion system: expression, purification and crystallization
JF  - Acta Crystallographica Section F
N2  - 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 Å 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 Å, α = β = γ = 90°.
KW  - ESAT‐6‐like secretion system
KW  - ESS
KW  - type VII secretion system
KW  - EsaA
KW  - extracellular domain
KW  - Staphylococcus aureus USA300
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-213681
VL  - 75
IS  - 12
ER  - 
TY  - JOUR
A1  - Mielich-Süss, Benjamin
A1  - Wagner, Rabea M.
A1  - Mietrach, Nicole
A1  - Hertlein, Tobias
A1  - Marincola, Gabriella
A1  - Ohlsen, Knut
A1  - Geibel, Sebastian
A1  - Lopez, Daniel
T1  - Flotillin scaffold activity contributes to type VII secretion system assembly in Staphylococcus aureus
JF  - PLoS Pathogens
N2  - Scaffold proteins are ubiquitous chaperones that promote efficient interactions between partners of multi-enzymatic protein complexes; although they are well studied in eukaryotes, their role in prokaryotic systems is poorly understood. Bacterial membranes have functional membrane microdomains (FMM), a structure homologous to eukaryotic lipid rafts. Similar to their eukaryotic counterparts, bacterial FMM harbor a scaffold protein termed flotillin that is thought to promote interactions between proteins spatially confined to the FMM. Here we used biochemical approaches to define the scaffold activity of the flotillin homolog FloA of the human pathogen Staphylococcus aureus, using assembly of interacting protein partners of the type VII secretion system (T7SS) as a case study. Staphylococcus aureus cells that lacked FloA showed reduced T7SS function, and thus reduced secretion of T7SS-related effectors, probably due to the supporting scaffold activity of flotillin. We found that the presence of flotillin mediates intermolecular interactions of T7SS proteins. We tested several small molecules that interfere with flotillin scaffold activity, which perturbed T7SS activity in vitro and in vivo. Our results suggest that flotillin assists in the assembly of S. aureus membrane components that participate in infection and influences the infective potential of this pathogen.
KW  - flotillin
KW  - scaffold protein
KW  - Staphylococcus aureus
KW  - type VII secretion system
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170035
VL  - 13
IS  - 11
ER  -