9.B.18 The Xanthan Glycosyl Transferase, GumD (GumD) Family

The GumD family cosists of a large number of glycosyltransferases involved in exo-polysaccharide biosynthesis and export.  GumD of Xanthomonas campestris is a costituent of a multicomponent system involved in the biosynthesis and export to the cell surface.  Some of the constituents of this system include GumB (TC# 1.B.18.3.7) and GumC (TC#8.A.3.1.3) (Bianco et al. 2014).  The N-terminus of GumD (residues 30 - 140) consists of a domain of closely packed 4 TMSs, followed by a hydrophilic domain that includes 1 or 2 additional TMSs.  Residues 75 - 275 consist of the NADB_Rossmann or CoA binding_3 domain, while residues 300 to the end consist of the Bacterial Transferase (bac_transf) domain of CDD. 


 

References:

Bianco, M.I., M. Jacobs, S.R. Salinas, A.G. Salvay, M.V. Ielmini, and L. Ielpi. (2014). Biophysical characterization of the outer membrane polysaccharide export protein and the polysaccharide co-polymerase protein from Xanthomonas campestris. Protein Expr Purif 101: 42-53.
Hegeman, A.D., J.W. Gross, and P.A. Frey. (2001). Probing catalysis by Escherichia coli dTDP-glucose-4,6-dehydratase: identification and preliminary characterization of functional amino acid residues at the active site. Biochemistry 40: 6598-6610.
Pérez-Burgos, M., I. García-Romero, J. Jung, E. Schander, M.A. Valvano, and L. Søgaard-Andersen. (2020). Characterization of the Exopolysaccharide Biosynthesis Pathway in Myxococcus xanthus. J. Bacteriol. 202:.
Yang, J., J. Zhang, Z. Zhu, X. Jiang, T. Zheng, and G. Du. (2022). Revealing novel synergistic defense and acid tolerant performance of Escherichia coli in response to organic acid stimulation. Appl. Microbiol. Biotechnol. [Epub: Ahead of Print]
Examples:

TC#NameOrganismal TypeExample
9.B.18.1.1

The glycosyl transferase, GumD, of 484 aas and 5 or 6 TMSs, involved in xanthan gum polysaccharide synthesis and export (Bianco et al. 2014).  The N-terminus consists of a closely packed 4 TMS domain (residues 30 - 140), followed by a hydrophilic domain that includes 1 or 2 additional TMSs.  Residues 75 - 275 consist of the NADB_Rossmann or CoA binding_3 domain, while residues 300 to the end consist of the Bacterial Transferase (bac_transf) domain of CDD.

Proteobacteria

GumD of Xanthomonas campestris

 
9.B.18.1.2

Exopolysaccharide biosynthesis polyprenyl glycosylphosphotransferase of 518 aas and 6 TMSs, 4 N-terminal and 2 more centrally located in the large hydrophilic domain.

Actinobacteria

Glycosyltransferase of Microbacterium laevaniformans

 
9.B.18.1.3

Putative UDP-N-acetylgalactosamine-undecaprenyl-phosphate N-acetylgalactosaminephosphotransferase of 453 aas and 7 TMSs.

Putative transferase of Pedobacter glucosidilyticus

 

 
9.B.18.1.4

UDP-Gal:undecaprenolphosphate Gal-1-P transferase WbaP with 376 aas and 5 TMSs in a 4 + 1 arrangement.

WbaP of E. coli

 
9.B.18.1.6

Polyisoprenyl-phosphate:hexose-1-P transferase, EpsZ (MXAN_7415), of 494 aas and 5 or 6 TMSs in a 4 or 5 TMS (residues 1 - 150 aas) plus 1 TMS at about residue 310. It is responsible for the initiation of repeat unit synthesis and has galactose-1-P transferase activity (Pérez-Burgos et al. 2020). Its gene is adjacent to the polysaccharide flippase, Wzx (TC# 2.A.66.12.12) and the outer membrane exopolysaccharide exporter (TC# 1.B.18.3.9).

EpsZ of Myxococcus xanthus

 
Examples:

TC#NameOrganismal TypeExample
9.B.18.2.1

Putative capsular polysaccharide biosynthetic enzyme, WbpM of 626 aas and 4 N-terminal TMSs.

WbpM of Bdellovibrio bacteriovorus

 
9.B.18.2.2

Polysaccharide biosynthesis protein of 640 aas and 4 N-terminal TMSs.

PS biosynthesis protein of Clostridium algidicarnis

 
9.B.18.2.3

Exopolysaccharide synthesis protein of 626 aas and 5 N-terminal TMSs.

EPS biosynthesis protein of Burkholderia vietnamiensis

 
9.B.18.2.4

dTDP-glucose 4,6-dehydratase 2, RffG, of 355 aas and possibly one N-terminal TMS. It catalyzes the dehydration of dTDP-D-glucose to form dTDP-6-deoxy-D-xylo-4-hexulose via a three-step process involving oxidation, dehydration and reduction (Hegeman et al. 2001). RffG increases the survival rate after exposure of E. coli to acid stress by 4500 times (Yang et al. 2022).

RffG of E. coli