Biomedical subjects

Simon Scheuring

Publications and source records attributed to Simon Scheuring.

21 records · Page 2Linked to original sources

PubMed2002

Sampling the conformational space of membrane protein surfaces with the AFM.

The atomic force microscope acquires topographs of single native membrane proteins at subnanometer resolution. Owing to the high signal-to-noise ratio, such images allow the conformational space of membrane protein surfaces to be sampled. This is demonstrated by topographs of porin OmpF, aquaporin-Z, and bacteriorhodopsin, all recorded at a lateral resolution of <7 A and a vertical resolution of ~1 A. The amplitudes of the domain movements were estimated from a large number of single molecule topographs and the corresponding energy landscapes calculated. To visualize the motion of protein domains, movies were generated by similarity ranking of the observed protein configurations. Electronic supplementary material to this paper can be obtained by using the Springer Link server located at http://dx.doi.org/10.1007/s00249-001-0197-8

Aquaporins↗

PubMed2002

Imaging and manipulation of biological structures with the AFM.

Many biologists have dreamt of physically touching and manipulating the biomolecules they were investigating. With the invention of the atomic force microscope (AFM), this dream has come true. Here, recent applications of the AFM to image and to manipulate biological systems at the nanometer scale are reviewed. Macromolecular biological assemblies as well as individual biomolecules can be subjected to controlled nanomanipulation. Examples of AFM application in imaging and nanomanipulation include the extraction of chromosomal DNA for genetic analysis, the disruption of antibody--antigen bonds, the dissection of biological membranes, the nanodissection of protein complexes, and the controlled modulation of protein conformations. Also reviewed is the novel combination of single molecule imaging and force spectroscopy which allows biomolecules to be imaged, and inter- and intramolecular forces to be measured. Future application of these nanotechniques will reveal new information on the structure, function and assembly of biomolecules.

Antigen-Antibody Complex↗

PubMed2002

Charting and unzipping the surface layer of Corynebacterium glutamicum with the atomic force microscope.

Bacterial surface layers (S-layers) are extracellular protein networks that act as molecular sieves and protect a large variety of archaea and bacteria from hostile environments. Atomic force microscopy (AFM) was used to asses the S-layer of Coryne-bacterium glutamicum formed of PS2 proteins that assemble into hexameric complexes within a hexagonal lattice. Native and trypsin-treated S-layers were studied. Using the AFM stylus as a nanodissector, native arrays that adsorbed to mica as double layers were separated. All surfaces of native and protease-digested S-layers were imaged at better than 1 nm lateral resolution. Difference maps of the topographies of native and proteolysed samples revealed the location of the cleaved C-terminal fragment and the sidedness of the S-layer. Because the corrugation depths determined from images of both sides span the total thickness of the S-layer, a three-dimensional reconstruction of the S-layer could be calculated. Lattice defects visualized at 1 nm resolution revealed the molecular boundaries of PS2 proteins. The combination of AFM imaging and single molecule force spectroscopy allowed the mechanical properties of the Corynebacterium glutamicum S-layer to be examined. The results provide a basis for understanding the amazing stability of this protective bacterial surface coat.

Bacterial Outer Membrane Proteins↗