9HU9

Glycosyltransferase C from the Limosilactobacillus reuteri accessory secretion system. Complex with UDP-GlcNAc.

Summary for 9HU9

• Entry DOI: 10.2210/pdb9hu9/pdb
• Related: 9HTX 9HUA
• Descriptor: Glucosyltransferase 3, URIDINE-5'-DIPHOSPHATE, CITRIC ACID, ... (8 entities in total)
• Functional Keywords: glycosyl transferase, gt113, transferase
• Biological source: Limosilactobacillus
• Total number of polymer chains: 4
• Total formula weight: 156440.49

Authors

Pfalzgraf, H.E.,Griffiths, R.,Juge, N.,Hemmings, A.M. (deposition date: 2024-12-21, release date: 2025-04-23, Last modification date: 2025-12-10)

Primary citation

Griffiths, R.,Pfalzgraf, H.,Latousakis, D.,Ashworth, G.,Dong, C.,Hemmings, A.,Juge, N.
A structural basis for the strain-dependent UDP-sugar specificity of glycosyltransferase C from the Limosilactobacillus reuteri accessory secretion system.
Acta Crystallogr D Struct Biol, 81:708-717, 2025

PubMed Abstract: The accessory secretion (aSec) system is a protein export pathway that is uniquely present in Gram-positive bacteria and is dedicated to the secretion of large, glycosylated cell wall-anchored adhesins called serine-rich repeat proteins (SRRPs). Strain-specific glycosylation of SRRPs has previously been reported in Limosilactobacillus reuteri and attributed to GtfC, a glycosyltransferase belonging to family 113, with LrGtfC from L. reuteri rat strain 100-23C showing specificity for UDP-Glc, while LrGtfC from L. reuteri pig strain ATCC 53608, which differs at only ten amino-acid positions, shows a preference for UDP-GlcNAc. However, the structural basis underpinning GtfC sugar-donor specificity remains unclear. Here, we report X-ray crystal structures of the tetrameric LrGtfC in the apo form and its complexes with UDP and with the noncognate sugar donor UDP-N-acetylglucosamine (UDP-GlcNAc). Analysis of the LrGtfC structures identified candidate residues implicated in donor-sugar substrate specificity, which were supported by site-directed mutagenesis. Reciprocal swaps of candidate residues combined with thermal shift assays revealed that the W240C variant of LrGtfC could bind both UDP-sugar donors, while the P243S variant of LrGtfC became specific for UDP-Glc, opening the door for glycoengineering approaches in bacteria.

PubMed: 41190658
DOI: 10.1107/S2059798325008782

Experimental method

X-RAY DIFFRACTION (2.4 Å)