A bifunctional O-antigen polymerase structure reveals a new glycosyltransferase family

Abstract

Lipopolysaccharide O-antigen is an attractive candidate for immunotherapeutic strategies targeting antibiotic-resistant Klebsiella pneumoniae. Several K. pneumoniae O-serotypes are based on a shared O2a-antigen backbone repeating unit;antigen is synthesized on undecaprenol diphosphate in a pathway involving the O2a polymerase, WbbM, prior to its export by an ABC transporter. This dual domain polymerase possesses a Cterminal galactopyranosyltransferase resembling known GT8 family enzymes, and an N-terminal DUF4422 domain identified here as a galactofuranosyltransferase defining a previously unrecognized family (GT111). Functional assignment of DUF4422 explains how galactofuranose is incorporated into various polysaccharides of importance in vaccine production and the food industry. In the 2.1 Å-resolution structure, three WbbM protomers associate to form a flattened triangular prism connected to a central stalk that orients the active sites towards the membrane.The biochemical, structural and topological properties of WbbM offer broader insight into the mechanisms of assembly of bacterial cell-surface glycans.

Chlorovirus PBCV-1 protein A064R has three of the transferase activities necessary to synthesize its capsid protein N-linked glycans

“…The oldest is KpsC, an enzyme with two GT activities that are involved in the biosynthesis of the Escherichia coli K5 polysaccharide (27). More recently, Clarke et al (28) discovered an O2a polymerase (WbbM) in Klebsiella pneumoniae that possesses two domains, a galactopyranosyltransferase resembling known GT8 family enzymes and a galactofuranosyltransferase defining a previously unrecognized family (GT111). Only a few other multidomain enzymes have been identified with more than one GT active site: WbdA mannosyltransferase involved in the synthesis of the E. coli O9, O9a, and O8 lipopolysaccharide O antigens, which is recognized as a bifunctional α-(1→2)-, α-(1→3)-mannosyltransferase in serotype O9a, while its counterpart in serotype O8 is a trifunctional mannosyltransferase (α-[1→2], α-[1→3], and β-[1→2]) (29,30).…”

Lipopolysaccharide O-antigens—bacterial glycans made to measure

“…1C) synthesis requires three GTs. Two adapter GTs add sequential Galp and Galf residues to Und-PP-GlcNAc (generated by WecA), directing it into the pathway, and the WbbM polymerase is solely responsible for extending the repeat-unit region of the glycan on this acceptor structure (78). WbbM is a dual GT domain protein that forms homotrimers, and the catalytic domains in each monomer are linked via a flexible tether to C-terminal membrane-associating amphipathic helices (78) (Fig.…”

Knockdown of lncRNA FEZF1-AS1 Inhibits metastasis of Osteosarcoma Cells by miR-4456/GALNT10

“…We bought the normal human osteoblast cell line hFOB1. 19 and osteosarcoma cell lines (143B, U2OS, MG63, and HOS) from the American Type Culture Collection (Manassas, VA). We cultured all the cell lines in Dulbecco's modi ed Eagle's medium (DMEM, (HyClone, Logan, USA) added with 10% fetal bovine serum (FBS, Gibco, NY, USA), 100 U/mL penicillin, and 100 mg/mL streptomycin (Baomanbio, Shanghai, China) and incubated in an incubator (5% CO 2 , 37°C).…”

“…Glycosyltransferase, also referred to as glycogene, is a kind of enzyme that moderates the modi cations of proteins and lipids [19]. It serves an essential function in normal cell development and other physiological processes [20].…”