2G8S

Crystal structure of the soluble Aldose sugar dehydrogenase (Asd) from Escherichia coli in the apo-form

Summary for 2G8S

• Entry DOI: 10.2210/pdb2g8s/pdb
• Descriptor: Glucose/sorbosone dehydrogenases, CALCIUM ION, PHOSPHATE ION, ... (5 entities in total)
• Functional Keywords: 6 bladed beta-propellor, pyrolloquinoline quinone (pqq), quinoprotein, sugar binding protein
• Biological source: Escherichia coli K12
• Total number of polymer chains: 2
• Total formula weight: 80231.21

Authors

Southall, S.M.,Doel, J.J.,Richardson, D.J.,Oubrie, A. (deposition date: 2006-03-03, release date: 2006-08-08, Last modification date: 2024-11-06)

Primary citation

Southall, S.M.,Doel, J.J.,Richardson, D.J.,Oubrie, A.
Soluble Aldose Sugar Dehydrogenase from Escherichia coli: A HIGHLY EXPOSED ACTIVE SITE CONFERRING BROAD SUBSTRATE SPECIFICITY.
J.Biol.Chem., 281:30650-30659, 2006

PubMed Abstract: A water-soluble aldose sugar dehydrogenase (Asd) has been purified for the first time from Escherichia coli. The enzyme is able to act upon a broad range of aldose sugars, encompassing hexoses, pentoses, disaccharides, and trisaccharides, and is able to oxidize glucose to gluconolactone with subsequent hydrolysis to gluconic acid. The enzyme shows the ability to bind pyrroloquinoline quinone (PQQ) in the presence of Ca2+ in a manner that is proportional to its catalytic activity. The x-ray structure has been determined in the apo-form and as the PQQ-bound active holoenzyme. The beta-propeller fold of this protein is conserved between E. coli Asd and Acinetobacter calcoaceticus soluble glucose dehydrogenase (sGdh), with major structural differences lying in loop and surface-exposed regions. Many of the residues involved in binding the cofactor are conserved between the two enzymes, but significant differences exist in residues likely to contact substrates. PQQ is bound in a large cleft in the protein surface and is uniquely solvent-accessible compared with other PQQ enzymes. The exposed and charged nature of the active site and the activity profile of this enzyme indicate possible factors that underlie a low affinity for glucose but generic broad substrate specificity for aldose sugars. These structural and catalytic properties of the enzymes have led us to propose that E. coli Asd provides a prototype structure for a new subgroup of PQQ-dependent soluble dehydrogenases that is distinct from the A. calcoaceticus sGdh subgroup.

PubMed: 16864586
DOI: 10.1074/jbc.M601783200

Experimental method

X-RAY DIFFRACTION (1.5 Å)