title: The effect of protein complexation on the mechanical stability of Im9.
abstract: Force mode microscopy can be used to examine the effect of mechanical manipulation on the noncovalent interactions that stabilize proteins and their complexes. Here we describe the effect of complexation by the high affinity protein ligand E9 on the mechanical resistance of the simple four-helical protein, Im9. When concatenated into a construct of alternating I27 domains, Im9 unfolded below the thermal noise limit of the instrument ( approximately 20 pN). Complexation of E9 had little effect on the mechanical resistance of Im9 (unfolding force approximately 30 pN) despite the high avidity of this complex (K(d) approximately 10 fM).
authors.affiliation: Institute of Molecular and Cellular Biology, University of Leeds, United Kingdom.
authors.forename: Eleanore
authors.initials: E
authors.lastname: Hann
authors.forename: Nadine
authors.initials: N
authors.lastname: Kirkpatrick
authors.forename: Colin
authors.initials: C
authors.lastname: Kleanthous
authors.forename: D Alastair
authors.initials: DA
authors.lastname: Smith
authors.forename: Sheena E
authors.initials: SE
authors.lastname: Radford
authors.forename: David J
authors.initials: DJ
authors.lastname: Brockwell
mesh_terms: D001696:Biomechanical Phenomena; D003087:Colicins / Q000737:chemistry* / Q000648:ultrastructure*; D004548:Elasticity; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D018625:Microscopy, Atomic Force / Q000379:methods*; D046912:Multiprotein Complexes / Q000737:chemistry / Q000648:ultrastructure; D011487:Protein Conformation; D011489:Protein Denaturation; D013314:Stress, Mechanical
chemical_list: D003087:Colicins; D029968:Escherichia coli Proteins; D046912:Multiprotein Complexes; C488858:immE8 protein, E coli