Primary Study Of The Protein-Protein Interaction Network In Mitochondrial Intermembrane Space

AIM:To explore the protein-protein interactions of human mitochondrial intermembrane space(IMS) and construct the protein-protein interaction map.METHODS:The coding genes of proteins mostly located in human IMS were cloned into both pDBLeu and pPC86 vectors.And the interacting proteins were screened by co-transformation and mating methods of yeast two-hybrid(Y2H) system.Part of the positive results were verified by GST-pull down or(and) Co-immunoprecipitation (Co-IP) assays,and the interesting negative Y2H results were confirmed by Co-IP simultaneously.The interactions were evaluated by bioinformatics.And the protein-protein interaction map was visualized by Cytoscape software.Then biology significances of this network were further analyzed by investigating relative literatures.RESULTS:Thirty-eight baits and forty-one preys were successfully cloned.The self-activited baits were eliminated.And 50 interactions involved 36 target proteins were obtained after Y2H screening and Co-IP assay.Among them two interactions are previously reported.Six novel interaction pairs were selected to tested by GST-Pull down or(and) Co-IP.Four interactions were confirmed.After evaluating the interactions by bioinformatics methods,we found 13 interactions(26%) whose partners show co-occurrence of the corresponding gene symbols in PubMed databases,while no interaction share same gene knockout phenotype.In GO co-annotation analysis,12 interaction partners(24.5%) appear at the same hierarchy level in the fourth onward depth.Each interaction was scored by integrating many parameters in bioinformatics analysis,resulting in 27 high confidence interactions(55%).The visible network graphs by Cytoscape software show that our dataset is complement for the exist IMS network. Based on the experimental results and analysis above we further discussed the biology significances of this network.CONCLUSION:A complicated interaction network is obtained among proteins in IMS, and the newly identified interactions may provide some important clues for investigating the biology processes and their molecular mechanisms in IMS.