||70 (Research article)
||Khakzad, Hamed; Happonen, Lotta; Tran Van Nhieu, Guy; Malmström, Johan; Malmström, Lars
||In vivo Cross-Linking MS of the Complement System MAC Assembled on Live Gram-Positive Bacteria.
||Front Genet (2020) 11 612475
||8 citations (journal impact: 3.79)
||Protein-protein interactions are central in many biological processes but they are challenging to characterize especially in complex samples. Protein cross-linking combined with mass spectrometry MS and computational modeling is gaining increased recognition as a viable tool in protein interaction studies. Here we provide insights into the structure of the multicomponent human complement system membrane attack complex MAC using cross-linking MS combined with computational macromolecular modeling. We developed an affinity procedure followed by chemical cross-linking on human blood plasma using live to enrich for native MAC associated with the bacterial surface. In this highly complex sample we identified over 100 cross-linked lysine-lysine pairs between different MAC components that enabled us to present a quaternary model of the assembled MAC in its native environment. Demonstrating the validity of our approach this MAC model is supported by existing X-ray crystallographic and electron cryo-microscopic models. This approach allows the study of protein-protein interactions in native environment mimicking their natural milieu. Its high potential in assisting and refining data interpretation in electron cryo-tomographic experiments will be discussed.