Research Of EF-Tu Multiple Protein Complex In Escherichia Coli

Elongation factor Tu (EF-Tu), one of the most abundant proteins in Escherichia coli, is a guanine nucleotide-binding protein that plays a key role in protein synthesis. It is highly conserved in all bacteria and located in cytoplasm. Recently, it has been reported as a new pathogen-associated molecular pattern (PAMP) molecule in Arabidopsis plants. However, information regarding to how the protein moved from cytoplasm to the environment and recognized by host cells is not available. .With the use of Ni-NTA and Mass spectrum methods, a multiple protein complex, named EF-Tu multiple protein complex, was determinate. This complex consisted of OmpA, OmpF, MdtE, and EF-Tu in cell membrane, respectively, being a multi-pass membrane protein with four out membrane domains, an outer membrane protein; an inner membrane protein and a soluble protein in Escherichia coli.Furthermore, the result was confirmed by Western blotting, Far-western blotting and CO-IP, indicating the full structure of EF-Tu multiple protein complex. Furthermore, three forms of protein-protein interactions, EF-Tu·OmpA , OmpF·OmpA and MdtE·OmpA, were characterized in cytoplasm for this multi-component complex.In secretome, this complex included OmpA, OmpF and EF-Tu, suggesting that MdtE was not companied with the other three proteins out of the cell. Importantly, the EF-Tu multiple protein complex in secretome was the components bound with human monocytic/macrophage cells, in which OmpA and EF-Tu could directly interacted with the host cells. This indicates that OmpA and OmpF play an important role in reorganization of EF-Tu by host cells and their further immune responses.In summary, EF-Tu multiple proteins complex was reported for the first time in present study. Furthermore, the diverse structures and functions of this complex associated with its locations of cytoplasm, cell membrane and secretive proteins were characterized. Our findings highlight the mechanism of EF-Tu out of the cells and are helpful in an understanding of EFTu-PAMPs...