Identification of a novel interaction between SMC1 DNA damage repair protein and Escherichia coli O157: H7 EspF using co-immunoprecipitation combined with mass spectrometry

Abstract

Background: It is known that the enterohemorrhagic Escherichia coli (EHEC) O157: H7 EspF is a multifunctional effector that triggers several damage processes in the host cells. However, in the process of EHEC O157: H7 infection, the interaction between EspF, its N- or C-terminus, and host proteins, are still unclear. Results: In this study, we used co-immunoprecipitation combined with mass spectrometry to screen EspF-interacting proteins. A total of 311 host proteins are detected. The N-terminus of EspF is found to interact with 192 proteins, whereas 205 proteins interact with the C-terminus of EspF. These proteins are mainly involved in RNA splicing, endoplasmic reticulum stress, and a variety of metabolic signaling pathways. We verify here for the first time that SMC1 interacts with EspF and more strongly with its C-terminus, and provide evidence that EspF increases p-SMC1 levels. p-SMC1, known to influence the S-phase cell cycle arrest and usually express during periods of DNA damage. Surprisingly, Mass spectrometry reveals that EspF can also phosphorylate H2AX, suggesting that EspF may directly mediate DNA damage through SMC1 phosphorylation.Conclusion: Taken together, this is the first study describing the interaction between EspF and SMC1. Our work lays a foundation for further research on directly EspF-mediated host cells’ DNA damage, apoptosis, and even colorectal carcinogenesis.