The Effector Protein BspF Regulates Apoptosis through the Crotonylation of p53.

The type IV secretion system (T4SS) can promote the intracellular survival and reproduction of . T4SS secretes effector proteins to act on cellular signaling pathways to inhibit the host's innate immune response and cause a chronic, persistent infection. can survive in host cells for a long time by inhibiting macrophage apoptosis and avoiding immune recognition. The effector protein, BspF, secreted by T4SS, can regulate host secretory transport and accelerate the intracellular replication of . BspF has an acetyltransferase domain of the GNAT (GCN5-related N-acetyltransferases) family, and in our previous crotonylation proteomics data, we have found that BspF has crotonyl transferase activity and crotonylation regulation of host cell protein in the proteomics data. Here, we found that BspF attenuates the crotonylation modification of the interacting protein p53, which reduces the p53 expression through the GNAT domain. BspF can inhibit the transcription and protein expression of downstream apoptotic genes, thereby inhibiting host cell apoptosis. Additionally, the Δ mutant stain promotes apoptosis and reduces the survival rate of in the cells. In conclusion, we identified that the T4SS effector protein BspF can regulate host cell apoptosis to assist in its long-term survival by attenuating crotonylation modification of p53 and decreasing p53 expression. Our findings reveal a unique mechanism of elucidating how regulates host cell apoptosis and promotes its proliferation through the secretion of effector proteins.