Pyruvate Substitutions on Glycoconjugates

Abstract

Glycoconjugates are the most diverse biomolecules of life. Mostly located at the cell surface, they translate into cell-specific “barcodes” and offer a vast repertoire of functions, including support of cellular physiology, lifestyle, and pathogenicity. Functions can be fine-tuned by non-carbohydrate modifications on the constituting monosaccharides. Among these modifications is pyruvylation, which is present either in enol or ketal form. The most commonly best-understood example of pyruvylation is enol-pyruvylation of N-acetylglucosamine, which occurs at an early stage in the biosynthesis of the bacterial cell wall component peptidoglycan. Ketal-pyruvylation, in contrast, is present in diverse classes of glycoconjugates, from bacteria to algae to yeast—but not in humans. Mild purification strategies preventing the loss of the acid-labile ketal-pyruvyl group have led to a collection of elucidated pyruvylated glycan structures. However, knowledge of involved pyruvyltransferases creating a ring structure on various monosaccharides is scarce, mainly due to the lack of knowledge of fingerprint motifs of these enzymes and the unavailability of genome sequences of the organisms undergoing pyruvylation. This review compiles the current information on the widespread but under-investigated ketal-pyruvylation of monosaccharides, starting with different classes of pyruvylated glycoconjugates and associated functions, leading to pyruvyltransferases, their specificity and sequence space, and insight into pyruvate analytics.

Identification ofCollimonasgene loci involved in the biosynthesis of a diffusible secondary metabolite with broad‐spectrum antifungal activity and plant‐protective properties

“…cplI ) which carried the transposon insertion in mutant 46A06 is annotated to code for a polysaccharide pyruvyl transferase family protein (accession number WP_081991923). Pyruvyl transferases catalyse the transfer of the pyruvate moiety to a saccharide target (Hager et al ., 2019). Proteins belonging to this functional family include CsaB (Fujinami and Ito, 2018; Hager et al ., 2018), WcaK (Stevenson et al ., 1996), AmsJ (Wang et al ., 2012) and PssM (Ivashina et al ., 2010), which are all involved in the production of exopolysaccharides (EPS), including secondary cell wall polymers in Bacillus species, colanic acid in Escherichia coli , amylovoran in Erwinia and EPS in Rhizobium leguminosarum respectively.…”

“…This annotation suggests a link between the production of the carenaemin peptide core and the polysaccharide synthesis gene cluster that was identified through mutant 60C09. Pyruvyl transferases add a pyruvyl group to monosaccharides and are typically mentioned in the context of cell surface polysaccharides (Hager et al ., 2019). One typical outcome of pyruvyl transferase activity is the formation of a ketal structure which bridges two hydroxyl groups of a monosaccharide residue through pyruvate, thus forming a ring structure (Hager et al ., 2019).…”

“…Pyruvyl transferases add a pyruvyl group to monosaccharides and are typically mentioned in the context of cell surface polysaccharides (Hager et al ., 2019). One typical outcome of pyruvyl transferase activity is the formation of a ketal structure which bridges two hydroxyl groups of a monosaccharide residue through pyruvate, thus forming a ring structure (Hager et al ., 2019). In this process, two hydrogens (2H) are removed from the sugar moiety and a C 3 H 4 O 2 group is added back, for a net addition of C 3 H 2 O 2 , which represents a monoisotopic mass of 70.005.…”

Modifications of cell wall polymers in Gram-positive bacteria by multi-component transmembrane glycosylation systems

“…Consistent with this, glycosyl modifications on these polymers have also been reported to play a role in processes such as pathogenesis, resistance to cationic antimicrobial peptides, and to serve as phage receptors (reviewed in Refs. [ 49 , 50 ]). As mentioned above, one notable exception is the multi-component transmembrane glycosylation system in B. anthracis, which appears to be essential for the actual assembly of the complex SCWP and viability of the organism [ 22 •• ].…”

Carbohydrate-Active Enzymes: Structure, Activity, and Reaction Products

“…Ketal-pyruvylation is present in diverse classes of glycoconjugates, produced in bacteria, algae, and yeast, but is absent in humans. The authors collected up-to-date information on the prevalent ketal-pyruvylation of monosaccharides, including specificity and sequence space of pyruvyltransferases, and provided insights into pyruvate analytics [20].…”