Conformational changes associated with L16P and T118M mutations in the membrane-embedded PMP22 protein, consequential in CMT-1A.
Peripheral myelin protein 22 (PMP22) resides in the plasma membrane and is required for myelin formation in the peripheral nervous system. Excess PMP22 mutants accumulate in the endoplasmic reticulum (ER) resulting in the inherited neuropathies of Charcot-Marie-Tooth disease. However, there was no evidence of the structure of PMP22 or how mutations affect its folding. Therefore, in this study, we combined bioinformatics and homology modeling approaches to obtain three-dimensional native and mutated PMP22 models and its anchoring to a POPC membrane, submitted to .5-μs MD simulations, to determine how the L16P and T118M mutations affect the conformational behavior of PMP22. In addition, we investigated the ability of the native and mutated species to accumulate in the ER, via interaction with RER1, by combining protein-protein docking and MD simulations, taking the conformations that were most representative of the native and mutated PMP22 systems and RER1 conformations. Principal component analysis over MD simulations revealed that L16P and T118M mutations resulted in increased structural instability compared to the native form, which is consistent with previous experimental findings of increased structural fluctuations along a loop connecting transmembrane α-helix1 and α-helix2. Docking and MD simulations coupled with the MMGBSA approach allowed the identification that the binding interface for the PMP22-RER1 complex takes place through transmembrane α-helix1 and α-helix2, with higher effective binding free energy values between the mutated PMP22 systems and RER1 than for the native PMP22, mainly through van der Waals interactions.
a Laboratorio de Modelado Molecular y Bioinformática de la Escuela Superior de Medicina , Instituto Politécnico Nacional , Plan de San Luis Y Diaz Mirón S/N, Col. Casco de Santo Tomas, Ciudad de México C.P. 11340 , México.
Martiniano
M
Bello
b Laboratorio de biotecnología y bioinformática genómica de la Escuela Nacional de Ciencias Biológicas , Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n , Col. Santo Tomás, Ciudad de México C.P. 11340 , México.
Mixtli J
MJ
Torres
b Laboratorio de biotecnología y bioinformática genómica de la Escuela Nacional de Ciencias Biológicas , Instituto Politécnico Nacional, Prolongación de Carpio y Plan de Ayala s/n , Col. Santo Tomás, Ciudad de México C.P. 11340 , México.
Alfonso
A
Méndez-Tenorio
a Laboratorio de Modelado Molecular y Bioinformática de la Escuela Superior de Medicina , Instituto Politécnico Nacional , Plan de San Luis Y Diaz Mirón S/N, Col. Casco de Santo Tomas, Ciudad de México C.P. 11340 , México.
José
J
Correa-Basurto
D000818:Animals; D002462:Cell Membrane / Q000235:genetics; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D009154:Mutation / Q000235:genetics*; D009185:Myelin Proteins / Q000235:genetics*; D000072756:Protein Conformation, alpha-Helical / Q000235:genetics; D017510:Protein Folding
D008565:Membrane Proteins; D009185:Myelin Proteins
PMP22; binding free energy calculations; charcot–marie–tooth; docking; molecular dynamics simulations