Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2012 Apr 18;134(15):6552-5.
doi: 10.1021/ja301723p. Epub 2012 Apr 10.

Fluorosugar Chain Termination Agents as Probes of the Sequence Specificity of a Carbohydrate Polymerase

Affiliations
Free PMC article

Fluorosugar Chain Termination Agents as Probes of the Sequence Specificity of a Carbohydrate Polymerase

Christopher D Brown et al. J Am Chem Soc. .
Free PMC article

Abstract

Naturally occurring carbohydrate polymers are ubiquitous. They are assembled by polymerizing glycosyltransferases, which can generate polysaccharide products with repeating sequence patterns. The fidelity of enzymes of this class is unknown. We report a method for testing the fidelity of carbohydrate polymerase pattern deposition: we synthesized fluorosugar donors and used them as chain termination agents. The requisite nucleotide fluorosugars could be produced from a single intermediate using the Jacobsen catalyst in a kinetically controlled separation of diastereomers. The resulting fluorosugar donors were used by the galactofuranosyltransferase GlfT2 from Mycobacterium tuberculosis, and the data indicate that this enzyme mediates the cell wall galactan production through a sequence-specific polymerization.

Figures

Figure 1
Figure 1
Left: The polymerase GlfT2 transfers the donor nucleotide sugar UDP-Galf (1) to synthetic acceptor substrates to generate galactan. An alternating Galf-β-(1,5)-Galf-β-(1,6) pattern is generated. Right: Donors 2 and 3, bearing fluorine atoms in place of key hydroxyl groups, can be used as chain termination agents to determine the fidelity of pattern generation for carbohydrate polymerases such as GlfT2.
Figure 2
Figure 2
Fluorosugar donors disrupt the alternating linkage pattern and terminate polymerization. GlfT2 can elongate acceptor 12 by one residue when donor 2 is supplied (A, top), or by two residues when donor 3 is used (A, bottom). MALDI-TOF traces show chain termination is a result of pattern disruption (B).
Scheme 1
Scheme 1
Fluorosugars 2 and 3 can be accessed from a common intermediate, vinyl furanose 4 (top). A kinetically controlled separation of epoxide diastereomers can be used as a synthetic divergence point and as a method to isolate stereodefined isomers 8 and 9 en route to the synthetic targets.

Similar articles

See all similar articles

Cited by 11 articles

See all "Cited by" articles

Publication types

MeSH terms

Feedback