Non-native interactions are critical for mechanical strength in PKD domains.
Experimental observation has led to the commonly held view that native state protein topology is the principle determinant of mechanical strength. However, the PKD domains of polycystin-1 challenge this assumption: they are stronger than predicted from their native structure. Molecular dynamics simulations suggest that force induces rearrangement to an intermediate structure, with nonnative hydrogen bonds, that resists unfolding. Here we test this hypothesis directly by introducing mutations designed to prevent formation of these nonnative interactions. We find that these mutations, which only moderately destabilize the native state, reduce the mechanical stability dramatically. The results demonstrate that nonnative interactions impart significant mechanical stability, necessary for the mechanosensor function of polycystin-1. Remarkably, such nonnative interactions result from force-induced conformational change: the PKD domain is strengthened by the application of force.
Forman
Julia R
JR
Cambridge University Chemical Laboratory, MRC Centre for Protein Engineering, Lensfield Road, Cambridge, CB2 1EW, UK.
Yew
Zu Thur
ZT
Institute of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
Qamar
Seema
S
Cambridge University Department of Medical Genetics, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge CB2 0XY, UK.
Sandford
Richard N
RN
Cambridge University Department of Medical Genetics, Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge CB2 0XY, UK.
Paci
Emanuele
E
Institute of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK. Electronic address: e.paci@leeds.ac.uk.
Clarke
Jane
J
Cambridge University Chemical Laboratory, MRC Centre for Protein Engineering, Lensfield Road, Cambridge, CB2 1EW, UK. Electronic address: jc162@cam.ac.uk.
D018625:Microscopy, Atomic Force; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D050396:TRPP Cation Channels / Q000737:chemistry / Q000378:metabolism*; D013816:Thermodynamics
D050396:TRPP Cation Channels