Fig. 5.

The catalytic triad and negatively charged substrate-binding aspartate are essential for cell cycle arrest function of the Cif family. Shown is the cell cycle distribution measured by flow cytometry analysis of DNA contents. (A) Effects of Cys → Ser mutations in the catalytic triad of Cif family effectors on cell cycle progression. Indicated EGFP-tagged constructs were transfected into 293T cells, and EGFP-positive cells were gated out and analyzed. (B) Effects of mutations in the catalytic triad of CHBP. Indicated purified recombinant CHBP proteins were delivered directly into HeLa cells synchronized at the G₁/S boundary. (C) Effects of mutations in the catalytic triad and the negatively charged substrate-binding pocket of Cif during EPEC infection.