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Charting and unzipping the surface layer of Corynebacterium glutamicum with the atomic force microscope
Author(s) -
Scheuring Simon,
Stahlberg Henning,
Chami Mohamed,
Houssin Christine,
Rigaud JeanLouis,
Engel Andreas
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02864.x
Subject(s) - force spectroscopy , s layer , corynebacterium glutamicum , atomic force microscopy , biophysics , layer (electronics) , crystallography , mica , bacteria , materials science , biology , chemistry , nanotechnology , composite material , genetics
Summary 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.