PDBsum entry 3mpb

Isomerase

PDB id: 3mpb

Contents

Protein chains

226 a.a.

Ligands

ACT ×2

FRU ×2

GOL

Metals

_MN ×2

Waters ×281

References listed in PDB file

Key reference

• Title: Structure-Based annotation of a novel sugar isomerase from the pathogenic e. Coli o157:h7.
• Authors: L.M.Van staalduinen, C.S.Park, S.J.Yeom, M.A.Adams-Cioaba, D.K.Oh, Z.Jia.
• Ref.: J Mol Biol, 2010, 401, 866-881.
• PubMed id: 20615418

Abstract

Prokaryotes can use a variety of sugars as carbon sources in order to provide a selective survival advantage. The gene z5688 found in the pathogenic E. coli O157:H7 encodes a 'hypothetical' protein of unknown function. Sequence analysis identified the gene product as a putative member of the cupin superfamily of proteins, but no other functional information was known. We have determined the crystal structure of the Z5688 protein at 1.6 A resolution and identified the protein as a novel E. coli sugar isomerase (EcSI) through overall fold analysis and secondary structure matching. Extensive substrate screening revealed that EcSI is capable of acting on d-lyxose and d-mannose. The complex structure of EcSI with fructose allowed the identification of key active site residues, and mutagenesis confirmed their importance. The structure of EcSI also suggested a novel mechanism for substrate binding and product release in a cupin sugar isomerase. Supplementation of a non-pathogenic E. coli strain with EcSI enabled cell growth on the rare pentose d-lyxose.