Biosynthesis of legionaminic acid and its incorporation into glycoconjugates

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1016/bs.mie.2017.06.042
AuthorSearch for: 1; Search for: 1; Search for: 1
Name affiliation
  1. National Research Council of Canada. Human Health Therapeutics
FormatText, Book chapter
Book titleChemical Glycobiology Part A. Synthesis, Manipulation and Applications of Glycans
Series titleMethods in Enzymology; no. 597
ISSN0076-6879
ISBN9780128114698
Pages187–207
Subjectlegionaminic; sialyltransferase; glycoconjugate; campylobacter; legionella
Abstract
Legionaminic acids are analogs of sialic acid that occur in cell surface glycoconjugates of several bacteria. Because legionaminic acids share the same stereochemistry as sialic acid but differ at C7 and C9, they are interesting analogs to probe the impact of varying exocyclic moieties (C7–C9) on biological activities such as susceptibilities to sialidases, interactions with Siglecs and immunogenicity. There are currently no reports on the bacterial enzymes that transfer legionaminic acids to these cell surface glycoconjugates, but some mammalian and bacterial sialyltransferases display donor promiscuity and can use CMP-Leg5,7Ac2 efficiently enough to transfer Leg5,7Ac2 to their natural acceptor glycans. When the natural activity with CMP-Leg5,7Ac2 is significant but relatively low, an alternate strategy has been to engineer versions with improved activity to transfer Leg5,7Ac2. Importantly, we have found that some bacterial sialyltransferases are very efficient for transferring Leg5,7Ac2 to small synthetic glycans with various aglycones. The two mammalian sialyltransferases that have been tested so far (porcine ST3Gal1 and human ST6Gal1) were found to be more efficient than the bacterial sialyltransferases for the modification of glycoproteins. We provide a review of the sialyltransferases selected to modify different types of glycoconjugates with Leg5,7Ac2, including small synthetic acceptors, glycolipids, and glycoproteins. In the first part, we also propose an optimized biosynthetic pathway for in vitro preparation of the donor CMP-Leg5,7Ac2, based on enzymes selected from two bacteria that naturally produce legionaminic acid.
Publication date
PublisherElsevier
Elsevier
LanguageEnglish
Peer reviewedYes
NPARC number23002617
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