27ON

Structural basis of UDP-GlcNAc recognition and glycosyl transfer by KfiA in Escherichia coli K5 heparosan biosynthesis

Summary for 27ON

• Entry DOI: 10.2210/pdb27on/pdb
• Related: 5Z8B
• Descriptor: KfiA protein, MANGANESE (II) ION, URIDINE-5'-DIPHOSPHATE, ... (5 entities in total)
• Functional Keywords: sulfotransferase, sulfation, transferase
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 49399.33

Authors

Maeda, K.,Sakamoto, A.,Matsuura, K.,Toyoda, K.,Hori, H.,Onishi, M.,Baba, Y.,Nishimoto, E.,Sugiura, N.,Teramoto, T.,Kakuta, Y. (deposition date: 2026-06-08, release date: 2026-10-28)

Primary citation

Maeda, K.,Sakamoto, A.,Matsuura, K.,Toyoda, K.,Hori, H.,Onishi, M.,Baba, Y.,Kawaguchi, Y.,Ishibashi, Y.,Okino, N.,Nishimoto, E.,Sugiura, N.,Teramoto, T.,Kakuta, Y.
Structural and functional analysis of KfiA, a UDP-GlcNAc transferase involved in Escherichia coli K5 heparosan biosynthesis.
Carbohydr.Res., 570:110123-110123, 2026

PubMed Abstract: Heparosan is a linear glycosaminoglycan-related polysaccharide produced as the capsular polysaccharide of Escherichia coli K5. Its biosynthesis requires alternating transfer of N-acetylglucosamine and glucuronic acid by the glycosyltransferases KfiA and KfiC, respectively, but the structural basis of KfiA function has remained unclear. Here, we determined crystal structures of a C-terminally truncated KfiA in the apo state and in complex with UDP and a metal ion tentatively assigned as Mn, and combined structural analysis with functional characterization. KfiA adopts a conserved GT-A fold with a well-defined nucleotide- and metal-binding center. Structural and biochemical analyses further distinguish the core donor-associated catalytic region from peripheral structural elements that contribute to efficient glycosyl transfer. Comparison with related glycosyltransferases reveals a conserved structural framework for UDP-GlcNAc utilization. These results provide a structural basis for understanding KfiA function and heparosan chain extension in the two-enzyme KfiA-KfiC system.

PubMed: 42854325
DOI: 10.1016/j.carres.2026.110123

Experimental method

X-RAY DIFFRACTION (1.68 Å)