Effects of Full-Length Borealin on the Composition and Protein−Protein Interaction Activity of a Binary Chromosomal Passenger Complex

摘要

The chromosomal passenger complex (CPC) comprises at least four protein components andnfunctions at various cellular localizations during different mitotic stages to ensure correct chromosomensegregation and completion of cytokinesis. Borealin, the most recently identified member of the CPC, isnan intrinsically unstructured protein of low solubility and stability. Recent reports have demonstrated thenformation of binary or ternary CPC subcomplexes incorporating short Borealin fragments in Vitro. Usingnisothermal titration calorimetry, we show that full-length Borealin, instead of a Borealin fragment possessingnthe complete Survivin and INCENP recognition sequence, is required for the composition of anBorealin-Survivin complex competent to interact with INCENP. In addition, we show evidence thatnfull-length Borealin, which forms high-order oligomers in its isolated form, is a monomer in thenBorealin-Survivin CPC subcomplex.