脱氮硫杆菌硫化合物载体SoxYZ蛋白的同源建模和结构分析

Homology Modeling and Structure Analysis of SoxYZ:A Carrier of Sulfur Compounds from Thiobacillus denitrificans

脱氮硫杆菌(Thiobacillus denitrificans)中的Sox蛋白在硫代谢过程中起着至关重要的作用,硫化合物需先与硫氧化基因族(sox)编码的蛋白质Sox YZ二聚体共价连接后才能与其他酶发生相互作用。利用同源建模法构建硫化合物载体Sox YZ蛋白的二聚体结构并验证了其合理性。二聚体相互作用分析发现Sox YZ蛋白的溶剂可及表面积(solvent accessible surface,SAS)为10 922.92,疏水率为50.85%;亚基Sox Y和Sox Z界面处共含有12个氢键和1个Π键来维持其三维结构的稳定性;二聚体表面呈现明显的正负电势互补,两亚基界面处氨基酸残基的VDW作用能和静电作用能分别为-80.925 13kcal/mol和-323.856 57kcal/mol,这说明静电作用是二聚体形成的主要驱动力;Sox Z亚基的残基Thr28、Arg31、Lys32、Ser64、Gly65、Val66、Ser67对Sox Y亚基活性位点构象的稳定有重要作用。

Sox system of Thiobacillus denitrificans plays a vital role in the metabolism of sulfur compounds, SoxYZ coding by the sulfur oxidizing gene cluster （sox） is known to be a sulfur covalently binding protein, which binds sulfur compounds to the other enzymes. The structure of SoxYZ heterodimer, the carrier of sulfur compounds, is constructed by using homology modeling and is proved to be reliable. Analysis of protein interactions find that the Solvent Accessible Surface（SAS） of SoxYZ is 10 922.9~2, hydrophobicity is 50.85% ; the interface between subunits SoxY and SoxZ contains a total of 12 hydrogen bonds and a pi bond which maintain the stability of the three-dimensional structure; the electrostatic potential of SoxYZ surface is obviously complementary, the VDW interaction energy and electrostatic interaction energy of residues at the interface is - 80. 925 13kcal / mol and - 323. 856 57kcal / mol, respectively which showed that the electrostatic interaction energy was the main driving force to form the heterodimer and the residues Thr28, Arg31, Lys32, Ser64, Gly65, Va166, Ser67 of SoxZ played an important role in the stability of active site of SoxY.