Analysis of self-assembly of S-layer protein slp-B53 from Lysinibacillus sphaericus.
The formation of stable and functional surface layers (S-layers) via self-assembly of surface-layer proteins on the cell surface is a dynamic and complex process. S-layers facilitate a number of important biological functions, e.g., providing protection and mediating selective exchange of molecules and thereby functioning as molecular sieves. Furthermore, S-layers selectively bind several metal ions including uranium, palladium, gold, and europium, some of them with high affinity. Most current research on surface layers focuses on investigating crystalline arrays of protein subunits in Archaea and bacteria. In this work, several complementary analytical techniques and methods have been applied to examine structure-function relationships and dynamics for assembly of S-layer protein slp-B53 from Lysinibacillus sphaericus: (1) The secondary structure of the S-layer protein was analyzed by circular dichroism spectroscopy; (2) Small-angle X-ray scattering was applied to gain insights into the three-dimensional structure in solution; (3) The interaction with bivalent cations was followed by differential scanning calorimetry; (4) The dynamics and time-dependent assembly of S-layers were followed by applying dynamic light scattering; (5) The two-dimensional structure of the paracrystalline S-layer lattice was examined by atomic force microscopy. The data obtained provide essential structural insights into the mechanism of S-layer self-assembly, particularly with respect to binding of bivalent cations, i.e., Mg2+and Ca2+. Furthermore, the results obtained highlight potential applications of S-layers in the fields of micromaterials and nanobiotechnology by providing engineered or individual symmetric thin protein layers, e.g., for protective, antimicrobial, or otherwise functionalized surfaces.
Laboratory for Structural Biology of Infection and Inflammation, Institute of Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King Platz 6, 20146, Hamburg, Germany.|Bioengineering Faculty, Sichuan University of Science and Engineering, Huixing Rd., Xueyuan Street 180, Zigong, 643000, Sichuan, China.
Jun
J
Liu
Laboratory for Structural Biology of Infection and Inflammation, Institute of Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King Platz 6, 20146, Hamburg, Germany.
Sven
S
Falke
Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany.
Bjoern
B
Drobot
Laboratory for Structural Biology of Infection and Inflammation, Institute of Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King Platz 6, 20146, Hamburg, Germany.|Center for Free-Electron Laser Science (CFEL), DESY, Notkestr. 85, 22607, Hamburg, Germany.
Dominik
D
Oberthuer
EMBL Hamburg, European Molecular Biology Laboratory, Notkestr. 85, 22607, Hamburg, Germany.
Alexey
A
Kikhney
Helmholtz Institute Freiberg for Resource Technology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany.
Tobias
T
Guenther
Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany.
Karim
K
Fahmy
EMBL Hamburg, European Molecular Biology Laboratory, Notkestr. 85, 22607, Hamburg, Germany.
Dmitri
D
Svergun
Laboratory for Structural Biology of Infection and Inflammation, Institute of Biochemistry and Molecular Biology, University of Hamburg, Martin-Luther-King Platz 6, 20146, Hamburg, Germany.
Christian
C
Betzel
Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany. j.raff@hzdr.de.|Helmholtz Institute Freiberg for Resource Technology, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328, Dresden, Germany. j.raff@hzdr.de.
Johannes
J
Raff
D001406:Bacillaceae; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D002413:Cations, Divalent / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D055550:Protein Stability / Q000187:drug effects; D017433:Protein Structure, Secondary
D001426:Bacterial Proteins; D002413:Cations, Divalent; D008562:Membrane Glycoproteins; C055764:S-layer proteins
AFM; Bivalent cations; DSC; SAXS; Self-assembly; Surface-layer protein