Mechanism of Ser88 phosphorylation-induced dimer dissociation in dynein light chain LC8.
Dynein light chain LC8 is a highly conserved, dimeric protein involved in a variety of essential cellular events. Phosphorylation at Ser88 was found to promote mammalian cell survival and regulate the dimer to monomer transition at physiological pH. Combining molecular dynamics (MD) simulation and free energy calculation methods, we explored the atomistic mechanism of the phosphorylation-induced dimer dissociation. The MD simulation revealed that phosphorylation/phosphomimetic mutation at Ser88 opens an entrance into the dimer interface for water molecules, which disturb the hydrogen bond network around His55 and is expected to raise the pK(a) value and protonation ratio of His55 as well. The free energy calculations showed that the S88E mutation destabilized the dimer by 6.6 kcal/mol, in good agreement with the experimental value of 8.1 kcal/mol. The calculated destabilization upon phosphorylation is 50.8 kcal/mol, showing that phosphorylation definitely prevents dimer formation under physiological conditions. Further analysis of the calculated free energy changes demonstrated that the electrostatic contribution dominates the impact of phosphorylation on dimer dissociation.
Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University, Shanghai 200433, People's Republic of China.
Fei
F
Xiao
Jingwei
J
Weng
Kangnian
K
Fan
Wenning
W
Wang
D056445:Cytoplasmic Dyneins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D056004:Molecular Dynamics Simulation; D009154:Mutation; D010766:Phosphorylation; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012694:Serine / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics
D010940:Plant Proteins; D012694:Serine; D056445:Cytoplasmic Dyneins