Novel Protein-Protein Interactions of the Yersinia pestis Type III Secretion System Elucidated With a Matrix Analysis by Surface Plasmon Resonance and Mass Spectrometry
NATIONAL CANCER INST FREDERICK MD
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Binary complexes formed by components of the Yersinia pestis type III secretion system were investigated by surface-plasmon resonance SPR and matrix-assisted laser desorption time-of-flight MALDI-TOF mass spectrometry. Pair-wise interactions between fifteen recombinant Yersinia outer proteins Yops, regulators and chaperones were first identified by SPR. Mass spectrometry confirmed over 80 of the protein-protein interactions suggested by SPR, and new binding partners were further characterized. The Yop secretion protein Ysc M2 of Y. enterocolitica and LcrQ of Y. pestis, formerly described as ligands only for the specific Yop chaperone Syc H, formed stable complexes with SycE. Additional previously unreported complexes of YscE with the translocation-regulator protein TyeA and the thermal-regulator protein YmoA, and multiple potential protein contacts by YscE, YopK, YopH, and LcrH were also identified. Because only stably folded proteins were examined, the interactions we identified are likely to occur either before or after transfer through the injectosome to mammalian host cells, and may have relevance to understanding disease processes initiated by the plague bacterium.
- Medicine and Medical Research