S. typhimurium sialidase

Scheme 9.11 Enzymatic transsialylation of four MPEG-DOXyl glycosides with sialidases from Vibrio cholerae and Salmonella typhimurium. V. cholerae sialylated in position 6 of the terminal monosaccharide units with yields of 12-17%, whereas S. typhimurium sialylated position 3 of the same monosaccharide units (yields 14-24%).

Figure 2. The sialidase superfamily (a) Influenza virus neuraminidase tetramer, (b) the small sialidases from S. typhimurium and (c) M. viridifaciens, (d) the side view of the large M. viridifaciens sialidase, (e) V. cholerae sialidase. The inhibitor Neu5Ac2en is shown bound in several active sites and galactose is also shown in the large M. viridifaciens sialidase. The isolated grey spheres represent divalent ions that play a key structural role in influenza and V. cholerae sialidase, and are an absolute requirement for activity.

In the first primary structures of microbial sialidases, obtained by cloning and sequencing of the respective genes from Clostridium perfringens [769], Vibrio cholerae [770], Clostridium sordellii [77 ] and Salmonella typhimurium [772], an amino acid sequence motif was detected, which is repeated four-fold in each protein S-X-D-X-G-X-T-W [773]. This motif, named the Asp-box, was found in all 16 sialidases of animals, trypanosomes, and bacteria, which have so far been sequenced (see refs. [660,768] and Table 18). In viral sialidases, however, the motif was rarely detectable (e.g. only the sialidase from N9 influenza A virus strain exhibits the complete motif [786] and has probably undergone mutational alterations). 

Hoyer, L. L., Hamilton, A. C., Steenbergen, S. M., and Vimr, E. R., 1992, Cloning, sequencing and distribution of the Salmonella typhimurium LT-2 sialidase gene, nanH, provides evidence for interspecies gene transfer. Mol. Microbiol. 6 873-884. 

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