The Tailspike Protein ofShigellaPhage Sf6

摘要: Bacteriophage Sf6 tailspike protein is functionally equivalent to the well characterized ofSalmonella phage P22, mediating attachment of viral particle host cell-surface polysaccharide. However, there significant sequence similarity between two 70-kDa polypeptides only in N-terminal putative capsid-binding domains. The major, central part P22 protein, which forms a parallel β-helix and responsible for saccharide binding hydrolysis, lacks detectable homology protein. After recombinant expression Escherichia coli as soluble was purified homogeneity. As shown by circular dichroism Fourier transform infrared spectroscopy, secondary structure contents proteins are very similar. Both tailspikes thermostable homotrimers resist denaturation SDS at room temperature. specific endorhamnosidase activities toward fluorescence-labeled dodeca-, deca-, octasaccharide fragments Shigella O-antigen suggest similar active site topology both proteins. Upon deletion domain, still thermostable, SDS-resistant trimer that has been crystallized. observations strongly trimeric with high structural its functional homolog from P22.