Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.4.99.7 (sialyltransferase)
 1,534 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The polysialosyl capsule in Escherichia coli K1 is not synthesized when cells are grown at 15 degrees C. Membranous sialyltransferase complexes isolated from cells grown at 15 degrees C spontaneously gain the ability to synthesize sialyl polymers when incubated at 33 degrees C for 2-4 h. Activation of the endogenous synthesis of polysialic acid is localized in a low-density vesicle fraction (Whitfield, C., Adams, D.A., and Troy, F.A. (1984) J. Biol. Chem. 259, 12769-12775). The low density vesicles catalyzed protein synthesis, and spontaneous activation required protein synthesis. Immune blotting confirmed the presence of protein synthesis initiation factor, IF2, and ribosomal protein S6, in the low-density vesicle fraction. Temperature-upshift experiments identified four membrane proteins whose synthesis was temporally correlated with in vitro activation. These proteins have apparent molecular masses of 40, 21, 17.5, and 16 kDA. Although the function of these proteins is not known, they may relate to a sialyltransferase activity required to initiate sialyl polymer assembly, to an endogenous acceptor, or to a porin that may facilitate channeling of the polysialosyl chains through the outer membrane.
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PMID:Biosynthesis and assembly of the polysialic acid capsule in Escherichia coli K1. Activation of sialyl polymer synthesis in inactivate sialyltransferase complexes requires protein synthesis. 638 3

We isolated serologically identical (by serovar determination and porin variable region [VR] typing) strains of Neisseria gonorrhoeae from an infected male and two of his monogamous female sex partners. One strain (termed 398078) expressed the L1 (Galalpha1 --> 4 [corrected] Galbeta1 --> 4Glcbeta1 --> 4HepI) lipooligosaccharide (LOS) structure exclusively; the other (termed 398079) expressed the lacto-N-neotetraose (LNT; Galbeta1 --> 4GlcNAcbeta1 --> 3Galbeta1 --> 4Glcbeta1 --> 4HepI) LOS structure. The strain from the male index case expressed both glycoforms and exhibited both immunotypes. Nuclear magnetic resonance analysis revealed that sialic acid linked to the terminal Gal of L1 LOS via an alpha2 --> 6 linkage and, as expected, to the terminal Gal of LNT LOS via an alpha2--> 3 linkage. Insertional inactivation of the sialyltransferase gene (known to sialylate LNT LOS) abrogated both L1 LOS sialylation and LNT LOS sialylation, suggesting a bifunctional nature of this enzyme in gonococci. Akin to our previous observations, sialylation of the LNT LOS of strain 398079 enhanced the binding of the complement regulatory molecule, factor H. Rather surprisingly, factor H did not bind to sialylated strain 398078. LOS sialylation conferred the LNT LOS-bearing strain complete (100%) resistance to killing by even 50% nonimmune normal human serum (NHS), whereas sialylation of L1 LOS conferred resistance only to 10% NHS. The ability of gonococcal sialylated LNT to bind factor H confers high-level serum resistance, which is not seen with sialylated L1 LOS. Thus, serum resistance mediated by sialylation of gonococcal L1 and LNT LOS occurs by different mechanisms, and specificity of factor H binding to sialylated gonococci is restricted to the LNT LOS species.
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PMID:Enhanced factor H binding to sialylated Gonococci is restricted to the sialylated lacto-N-neotetraose lipooligosaccharide species: implications for serum resistance and evidence for a bifunctional lipooligosaccharide sialyltransferase in Gonococci. 1623 38