Imaging and detecting molecular interactions of single transmembrane proteins.
Single-molecule atomic force microscopy (AFM) provides novel ways to characterize structure-function relationships of native membrane proteins. High-resolution AFM-topographs allow observing substructures of single membrane proteins at sub-nanometer resolution as well as their conformational changes, oligomeric state, molecular dynamics and assembly. Complementary to AFM imaging, single-molecule force spectroscopy experiments allow detecting molecular interactions established within and between membrane proteins. The sensitivity of this method makes it possible to detect the interactions that stabilize secondary structures such as transmembrane alpha-helices, polypeptide loops and segments within. Changes in temperature or protein-protein assembly do not change the position of stable structural segments, but influence their stability established by collective molecular interactions. Such changes alter the probability of proteins to choose a certain unfolding pathway. Recent examples have elucidated unfolding and refolding pathways of membrane proteins as well as their energy landscapes. We review current and future potential of these approaches to reveal insights into membrane protein structure, function, and unfolding as we recognize that they could help answering key questions in the molecular basis of certain neuro-pathological dysfunctions.
Janovjak
Harald
H
Center of Biotechnology, University of Technology and Max-Planck-Institute of Molecular Cell Biology and Genetics, Tatzberg 49, D-01307 Dresden, Germany.
Kedrov
Alexej
A
Cisneros
David A
DA
Sapra
K Tanuj
KT
Struckmeier
Jens
J
Muller
Daniel J
DJ
D000818:Animals; D018360:Crystallography, X-Ray / Q000379:methods; D003952:Diagnostic Imaging; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011487:Protein Conformation; D017510:Protein Folding; D020539:Sequence Analysis, Protein; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
D008565:Membrane Proteins