PDBsum entry 4xsu

Transferase

PDB id: 4xsu

Contents

Protein chains

367 a.a.

Ligands

GLC ×2

UDP ×2

SO4 ×9

GOL

Waters ×219

PDB id:

4xsu

Name:

Transferase

Title:

Crystal structure of anabaena alr3699/hepe in complex with udp and glucose

Structure:

Alr3699 protein. Chain: b, a. Engineered: yes

Source:

Nostoc sp. (Strain pcc 7120 / utex 2576). Organism_taxid: 103690. Strain: pcc 7120 / utex 2576. Gene: alr3699. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.48Å R-factor: 0.225 R-free: 0.267

Authors:

X.P.Wang,Y.N.Dai,Y.L.Jiang,W.Cheng,Y.X.Chen,C.Z.Zhou

Key ref:

X.P.Wang et al. (2016). Structural and enzymatic analyses of a glucosyltransferase Alr3699/HepE involved in Anabaena heterocyst envelop polysaccharide biosynthesis. Glycobiology, 26, 520-531. PubMed id: 26692049 DOI: 10.1093/glycob/cwv167

Date:

22-Jan-15 Release date: 13-Jan-16

Protein chains

Q8YQW3  (Q8YQW3_NOSS1) -  Alr3699 protein from Nostoc sp. (strain PCC 7120 / SAG 25.82 / UTEX 2576)

Seq: 382 a.a.

Struc: 367 a.a.

Enzyme reactions

• Enzyme class: E.C.2.4.1.- - ?????

DOI no: 10.1093/glycob/cwv167

Glycobiology 26:520-531 (2016)

PubMed id: 26692049

Structural and enzymatic analyses of a glucosyltransferase Alr3699/HepE involved in Anabaena heterocyst envelop polysaccharide biosynthesis.

X.P.Wang, Y.L.Jiang, Y.N.Dai, W.Cheng, Y.Chen, C.Z.Zhou.

ABSTRACT

Formation of the heterocyst envelope polysaccharide (HEP) is a key process for cyanobacterial heterocyst differentiation. The maturation of HEP inAnabaenasp. strain PCC 7120 is controlled by a gene cluster termed HEP island in addition to an operonalr3698-alr3699, which encodes two putative proteins termed Alr3698/HepD and Alr3699/HepE. Here we report the crystal structures of HepE in the apo-form and three complex forms that bind to UDP-glucose (UDPG), UDP&glucose, and UDP, respectively. The overall structure of HepE displays a typical GT-B fold of glycosyltransferases, comprising two separate β/α/β Rossmann-fold domains that form an inter-domain substrate-binding crevice. Structural analyses combined with enzymatic assays indicate that HepE is a glucosyltransferase using UDPG as a sugar donor. Further site-directed mutageneses enable us to assign the key residues that stabilize the sugar donor and putative acceptor. Based on the comparative structural analyses, we propose a putative catalytic cycle of HepE, which undergoes "open-closed-open" conformational changes upon binding to the substrates and release of products. These findings provide structural and catalytic insights into the first enzyme involved in the HEP biosynthesis pathway.