Hydration behavior at the ice-binding surface of the Tenebrio molitor antifreeze protein.
Molecular dynamics (MD) simulations have been carried out at two different temperatures (300 and 220 K) to study the conformational rigidity of the hyperactive Tenebrio molitor antifreeze protein (TmAFP) in aqueous medium and the structural arrangements of water molecules hydrating its surface. It is found that irrespective of the temperature the ice-binding surface (IBS) of the protein is relatively more rigid than its nonice-binding surface (NIBS). The presence of a set of regularly arranged internally bound water molecules is found to play an important role in maintaining the flat rigid nature of the IBS. Importantly, the calculations reveal that the strategically located hydroxyl oxygens of the threonine (Thr) residues in the IBS influence the arrangements of five sets of ordered waters around it on two parallel planes that closely resemble the basal plane of ice. As a result, these waters can register well with the ice basal plane, thereby allowing the IBS to preferentially bind at the ice interface and inhibit its growth. This provides a possible molecular reason behind the ice-binding activity of TmAFP at the basal plane of ice.
Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology , Kharagpur 721302, India.
Uday Sankar
US
Midya
Sanjoy
S
Bandyopadhyay
D000818:Animals; D021301:Antifreeze Proteins / Q000737:chemistry*; D001665:Binding Sites; D007053:Ice / Q000032:analysis; D019476:Insect Proteins / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D011487:Protein Conformation; D013696:Temperature; D013712:Tenebrio / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D021301:Antifreeze Proteins; D007053:Ice; D019476:Insect Proteins; D014867:Water