Cell Surface Engineering for Molecular Recognition

[Guest guest]

Well well , right on cue ,I posted last week on the possibility of engineering a marker gene to illuminate & mark for destruction stealth pathogens ..I've just received this months "Marker Gene Monthly Newsletter April, 2005 Volume 5, Number 4.... & look what's included ...looks like the therapy is not quite as sci fi & could be closer than we think ...

Cell Surface Engineering for Molecular Recognition.Cells display on their surfaces a complex mixture of receptors and ligands that mediate cell adhesion, immune recognition and cell communication. Viruses also find convenient attachment points on these cell surface receptors. These ligands and receptors are often decorated with sugar polymers (oligosaccharides, glycans) whose structures are quite specific for attachment or communication. Recent work by Dr. Carolyn Bertozzi and co-workers at the University of California-Berkeley have centered on engineering new, and interesting receptors on cell surfaces by feeding the cells a sugar analog (Man-Lev) that they incorporate into their cell surface oligosaccharides as a modified version of the sugar sialic acid (5-NAcNeu). Since this sugar is usually found on the very outermost edges of the cell surface glycoproteins, the modified sugar that contains an aldehyde function can then be used to attach a second molecule, like biotin-hydrazide (M0128), thereby making a new "synthetic" cell surface receptor. Typically cells in culture are simply incubated with 25 mM N-levulinoyl-D-mannosamine (ManLev) or even more effectively with 25 µM ManLev tetraacetate. These ketone-containing monosaccharides serve as substrates in an oligosaccharide synthesis pathway, resulting in ketone-tagged cell-surface oligosaccharides. Other sugars, like GlcLev, have not been found to function as effectively for such modifications. For more information about these very interesting, new reagents and methods for cell surface labeling, please see the references below or visit our website.· Karema K.J., Bertozzi C.R., (1998) "Chemical Approaches to Glycobiology and Emerging Carbohydrate-Based Therapeutic Agents." Curr. Opin. Chem. Biol. 2: 49.· Yarema K.J., Mahal L.K., Bruehl R.E., E.C., Bertozzi C.R., (1998) "Metabolic delivery of ketone groups to sialic acid residues. Application To cell surface glycoform engineering." J. Biol. Chem. 273: 31168-31179.· Mahal L.K., Yarema K.J., Bertozzi C.R., (1997) "Engineering chemical reactivity on cell surfaces through oligosaccharide biosynthesis." Science 276: 1125-1128.· s C.L., Yarema K.J., Mahal L.K., Nauman D.A., Charters N.W., Bertozzi C.R., (2000) "Metabolic labeling of glycoproteins with chemical tags through unnatural sialic acid biosynthesis." Methods Enzymol. 327: 260-275.· Charter N.W., Mahal L.K., Koshland D.E., Jr, Bertozzi C.R., (2000) "Biosynthetic incorporation of unnatural sialic acids into polysialic acid on neural cells." Glycobiology 10: 1049-1056 (2000).· Sampson N.S., Mrksich M., Bertozzi C.R. (2001) "Surface molecular recognition." Proc Natl Acad Sci U S A 98, 12870-1.· Yarema K.J., (2001) "Directions in carbohydrate engineering: a metabolic substrate-based approach to modify the cell surface display of sialic acids." Biotechniques 31: 384-393.