Abstract: The aim of this study was to clone and bioinformatics analyze cya gene of Salmonella Typhimurium.cya gene was amplified from the Salmonella Typhimurium SL1344 strain by PCR and the sequence was cloned into pET-32a (+) vector for expression in Escherichia coli BL21 (DE3) cells and induced by addition of 1 mmol/L IPTG.At the same time,online bioinformatics software was used to analyze its bioinformatics.The results showed that cya gene from Salmonella Typhimurium was 1 185 bp.SDS-PAGE and Western blotting results showed that Cya expressed in the prokaryotic expression system was a inclusion body protein with a molecular weight of about 58 ku.Bioinformatics analysis results showed that cya gene of Salmonella Typhimurium was encoding a protein of 394 amino acids.The theoretical molecular weight of Cya protein was 44.97 ku,the molecular formular was C₂₀₂₆H₃₁₄₆N₅₆₂O₅₇₈S₁₁,and the isoelectric point(pI) was 7.01.The total number of negatively charged residues (Asp+Glu) and positively charged residues (Arg+Lys) were 43 and 42,respectively.Cya protein was a membrane protein without signal peptide and transmembrane region,containing 4 N-glycosylation sites,1 O-glycosylation sites,27 phosphorylation sites,13 linear B-cell epitopes and 11 T-cell epitopes.The secondary structure of Cya protein contained alpha helix (38.07%),extended chain (19.80%),beta turn (5.58%) and random coil (36.55%).The results laid a foundation for further study on the function of Cya protein of Salmonella Typhimurium and the establishment of an immunoassay method using Cya protein as antigen.

Key words: Salmonella Typhimurium; cya gene; prokaryotic expression; bioinformatics analysis