China Animal Husbandry and Veterinary Medicine ›› 2022, Vol. 49 ›› Issue (11): 4168-4177.doi: 10.16431/j.cnki.1671-7236.2022.11.007

• Biotechnology • Previous Articles     Next Articles

Prokaryotic Expression and Bioinformatics Analysis of avrA Protein of Salmonella Enteritidis

XU Yunming1, BU Yongqian1, BIAN Rongrong2, YANG Jianbo1, SUN Zhiyuan1, CHEN Yi1, LIU Zengshan3, REN Honglin3   

  1. 1. Institute of Animal Husbandry and Veterinary Medicine, Jiangsu Vocational College of Agriculture and Forestry, Jurong 212400, China;
    2. Bureau of Agricultural and Rural Affairs of Jurong, Jurong 212400, China;
    3. Key Laboratory of Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun 130062, China
  • Received:2022-04-13 Online:2022-11-05 Published:2022-11-04

Abstract: 【Objective】 The aim of this study was to express avrA protein of Salmonella Enteritidis which had biological activity and analyze its bioinformatics, so as to provide references for studying the influence of avrA protein of Salmonella Enteritidis on the immune function of porcine intestinal cells.【Method】 Primers were designed according to the complete gene sequence of avrA protein of Salmonella Enterititis in GenBank (gene ID:1254388), and avrA gene was amplified by PCR.After recombination and cloning of the recovered target fragment and expression vector PGEX-4T-1, the correctness of the recombinant expression plasmid was verified by restriction enzyme and gene sequencing.The verified recombinant expression plasmids were transformed into Escherichia coli Rosetta 2(DE3) competent cells, and the recombinant expression strains were induced to express under different conditions.The expression of avrA protein was detected by SDS-PAGE and Western blotting.The target gene sequences were analyzed by BLAST, and the amino acid composition of avrA protein was predicted by ExPASy-Translate Tool software.The transmembrane domain, secondary structure, tertiary structure and antigenicity of the target protein were predicted by bioinformatics softwares.【Result】 The total length of CDS region of avrA gene was 909 bp, encoding 302 animo acids.The recombinant expression plasmid PGEX-4T-1-avrA was successfully constructed by restriction enzyme and gene sequencing analysis.The results of SDS-PAGE and Western-blotting showed that avrA protein expressed by recombinant bacteria was soluble protein.The protein content of recombinant bacteria induced under 15 ℃ for 16 h was 10 mg/L and the protein solubility was 40%.Bioinformatics analysis showed that avrA protein was an extracellular protein, and amino acids 16-301 of avrA protein had a conserved domain from the superfamily YopJ serine/threonine acetyltransferase.In the secondary structure of avrA protein, random coil, alpha helix and extended chain were accounted for 43.71%, 39.40% and 16.89%, respectively.The predicted tertiary structure of avrA protein was consistent with the predicted secondary structure. AvrA protein had 9 B cell-binding epitopes at amino acid positions 5-40, 51-68, 80-92, 94, 101-109, 146-157, 160-168, 199-231, 236-298, respectively.【Conclusion】 avrA gene of Salmonella Enteritidis was successfully cloned, and the recombinant expression plasmid and expression bacteria were successfully constructed.The induced expressed avrA protein was soluble.AvrA protein was an extramembrane protein with 9 epitopes that could bind to B cells.The results of this study could provide references for the preparation of antibodies to detect Salmonella Enteritidis infection.

Key words: Salmonella Enteritidis; avrA protein; prokaryotic expression; bioinformatics analysis

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