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Articles by S Watarai
Total Records ( 2 ) for S Watarai
  Y Kushi , H Kamimiya , H Hiratsuka , H Nozaki , H Fukui , M Yanagida , M Hashimoto , K Nakamura , S Watarai , T Kasama , H Kajiwara and T. Yamamoto
 

Bacterial sialyltransferases (STs) from marine sources were characterized using glycosphingolipids (GSLs). Bacterial STs were found to be β-galacotoside STs. There were two types of STs: (1) ST obtained from strains such as ishi-224, 05JTC1 (#1), ishi-467, 05JTD2 (#2), and faj-16, 05JTE1 (#3), which form 2-3 sialic acid (Sia) linkages, named 2-3ST, (2) ST obtained from strains such as ISH-224, N1C0 (#4), pda-rec, 05JTB2 (#5), and pda-0160, 05JTA2 (#6), which form 2-6 Sia linkages, named 2-6ST. All STs showed affinity to neolacto- and lacto-series GSLs, particularly in neolactotetraosyl ceramide (nLc4Cer). No large differences were observed in the pH and temperature profiles of enzyme activities. Kinetic parameters obtained by Lineweaver–Burk plot analysis showed that #3 and #4 STs had practical synthetic activity and thus it became easily possible to achieve large-scale ganglioside synthesis (100–300 µM) using these recombinant enzymes. Gangliosides synthesized from nLc4Cer by 2-3 and 2-6STs were structurally characterized by several analytical and immunological methods, and they were identified as IV3NeuAc-nLc4Cer(S2-3PG) and IV6NeuAc-nLc4Cer (S2-6PG), respectively. Further characterization of these STs using lactotetraosylceramide (Lc4Cer), neolactohexaosylceramide (i antigen), and IV6kladoLc8Cer (I antigen) showed the synthesis of corresponding gangliosides as well. Synthesized gangliosides showed binding activity to the influenza A virus [A/panama/2007/99 (H3N2)] at a similar level to purified S2-3PG and S2-6PG from mammalian sources. The above evidence suggests that these STs have unique features, including substrate specificities restricted to lacto- and neolactoseries GSLs, as well as catalytic potentials for ganglioside synthesis. This demonstrates that efficient in vitro ganglioside synthesis could be a valuable tool for selectively synthesizing Sias modifications, thereby permitting the exploration of unknown functions.

  H Nozaki , M Yanagida , K. i Koide , K Shiotani , M Kinoshita , Y Kobayashi , S Watarai , K Nakamura , A Suzuki , T Ariga and Y. Kushi
 

We have established hybridoma cell lines producing monoclonal antibodies (mAbs) directed to N-acetylglucosaminylβ1-3galactose (GlcNAcβ1-3Gal) residue by immunizing BALB/c mice with lactotriaosylceramide (Lc3Cer). These obtained hybridoma cells, specific to Lc3Cer, were dual immunoglobulin (Ig)-producing cells which secreted both IgM and IgG molecules as antibodies. The established mAbs are able to react with not only Lc3Cer but also GlcNAcβ1-3-terminal glycosphingolipids (GSLs) despite branching or lactosamine chain lengths and human transferrin with terminal GlcNAc residues. Comparison of the variable regions of the cloned IgM and IgG by reversed transcription-polymerase chain reaction analysis confirmed that the variable regions determine the specificity, the other amino acids are conserved, and these mAbs are encoded by J558 and V-21family genes. Furthermore, we have analyzed the expression of GSLs with GlcNAcβ1-3 epitope in acute leukemia cell lines and mouse fetal tissues using these mAbs, in which antigens were distributed comparatively. These mAbs are useful for studying the precise distribution of GlcNAcβ1-3Gal-terminating GSL expression in tissues as well as for detecting GSLs carrying terminal GlcNAcβ1-3Gal carbohydrate structure.

 
 
 
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