Crystal Structure And Function Of Acetyl-transferase ElaA From Escherichia Coli

Acetylation is a phenomenon of post-translational modification of proteins that are widely present in eukaryotic and prokaryotic cells.Acetyl donors(such as acetyl-CoA and other small molecules)can transfer acetyl groups under the catalytic action of acetyltransferases to the substrate protein related amino acid residues.Current studies on acetyltransferases have focused on eukaryotes,and there are few studies in prokaryotes.ElaA protein is widely distributed in a variety of bacteria and has high homology in different strains.They are considered to be a type of acetyltransferase,however,there is still a lack of in-depth research on the definition of this function and specific substrates.In this study,the three-dimensional structure and functional relationships of ElaA(EcElaA)derived from the E.coli K-12 strain were studied.We have performed large-scale expression and purification of EcElaA,and purified the protein for crystallization screening to obtain X-ray diffraction quality crystals.By collecting diffraction data,we solved the crystal structure with a resolution of 2.60 A.The structure indicates that EcElaA possesses the typical structural features of the GCN5-related N-acetyltransferase(GNAT)family and consists of seven anti-parallel ?-sheets and four a-helices.Through structural alignment,it was found that the three-dimensional conformation of the SACOL1063-AcCoA complex from another member of the GNAT family in Staphylococcus aureus was highly similar to that of a superimposed structure.It was concluded that there are similar acetyl-CoA binding sites and receptors substrate binding site in EcElaA.After ultracentrifugation analysis,it was found that EcElaA mainly exists as a dimer in solution,and the results of isothermal titration calorimetry(ITC)experiments show that small molecule acetyl-CoA interacts with EcElaA.Then we screened the crystals of the EcElaA-AcCoA complex.After a lot of crystallization optimization,X-ray diffraction quality crystals could not be obtained.The EcElaA-AcCoA complex crystals and the exploration of the interaction of EcElaA with possible substrates point the way for the structural analysis of acetyltransferases in other prokaryotes,and also provide insights into the proteosome's role of this type of acetyltransferase in cells.The mechanism of action and the corresponding biological functions lay the foundation.