Screening and structure analysis of Helicobacter pylori urease nanobody
Objective To screen the nanobody against Helicobacter pylori(H.pylori)urease based on the nanobody library,analyze the structure and binding site,and to identify its inhibitory effect on the activity of urease.Methods Through the display library of natural alpaca phage antibody,using urease B subunit as the target antigen,the nanobody against H.pylori urease was obtained by four rounds of washing and positive clone screening.The nanobody structure and the space binding region with urease were analyzed by structure prediction software,and the inhibitory effect of urease nanobody on urease activity was determined.Results Three nanobodies against H.pylori urease B subunit were obtained.The sequence homology of the three nanobodies was 78.43％,and the variable regions were all hydrophobic amino acids,containing more β folds and Loop regions.Closer and wider contact was formed at the same site in the 3D models,which was formed with the sites of 301-312,371-385,440-460 and 550-570 of urease B.When combined with urease B,all of the three nanobodies formed steric hindrance,which interfered with the formation of the dimer of urease A and B subunits,thus inhibiting the function of urease.Conclusion The obtained high affinity anti-urease nanobodies can inhibit the urease activity,which provides an experimental basis for the subsequent preparation of H.pylori urease diagnostic antibody and the research for new therapeutic targets.
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