title: A single disulfide bond disruption in the β3 integrin subunit promotes thiol/disulfide exchange, a molecular dynamics study.
abstract: The integrins are a family of membrane receptors that attach a cell to its surrounding and play a crucial function in cell signaling. The combination of internal and external stimuli alters a folded non-active state of these proteins to an extended active configuration. The β3 subunit of the platelet αIIbβ3 integrin is made of well-structured domains rich in disulfide bonds. During the activation process some of the disulfides are re-shuffled by a mechanism requiring partial reduction of some of these bonds; any disruption in this mechanism can lead to inherent blood clotting diseases. In the present study we employed Molecular Dynamics simulations for tracing the sequence of structural fluctuations initiated by a single cysteine mutation in the β3 subunit of the receptor. These simulations showed that in-silico protein mutants exhibit major conformational deformations leading to possible disulfide exchange reactions. We suggest that any mutation that prevents Cys560 from reacting with one of the Cys(567)-Cys(581) bonded pair, thus disrupting its ability to participate in a disulfide exchange reaction, will damage the activation mechanism of the integrin. This suggestion is in full agreement with previously published experiments. Furthermore, we suggest that rearrangement of disulfide bonds could be a part of a natural cascade of thiol/disulfide exchange reactions in the αIIbβ3 integrin, which are essential for the native activation process.
authors.affiliation: Biochemistry and Molecular Biology Department, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Lihie
authors.initials: L
authors.lastname: Levin
authors.forename: Ehud
authors.initials: E
authors.lastname: Zelzion
authors.forename: Esther
authors.initials: E
authors.lastname: Nachliel
authors.forename: Menachem
authors.initials: M
authors.lastname: Gutman
authors.forename: Yossi
authors.initials: Y
authors.lastname: Tsfadia
authors.forename: Yulia
authors.initials: Y
authors.lastname: Einav
mesh_terms: D002450:Cell Communication / Q000502:physiology*; D016000:Cluster Analysis; D019295:Computational Biology; D004220:Disulfides / Q000737:chemistry*; D006801:Humans; D039661:Integrin beta3 / Q000737:chemistry* / Q000235:genetics; D056004:Molecular Dynamics Simulation; D009154:Mutation / Q000235:genetics; D021122:Protein Subunits / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D004220:Disulfides; D039661:Integrin beta3; D021122:Protein Subunits; D013438:Sulfhydryl Compounds