Analysis of Protein Solvent Interactions in Glucose Dehydrogenase from the Extreme Halophile Haloferax mediterranei

The structure of glucose dehydrogenase from the extreme halophile Haloferax mediterranei has been solved at 1.6-Å resolution under crystallization conditions which closely mimic the "in vivo" intracellular environment. The decoration of the enzyme's surface with acidic residues is onl...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2006-03, Vol.103 (13), p.4846-4851
Main Authors: Britton, K. Linda, Baker, Patrick J., Fisher, Martin, Ruzheinikov, Sergey, Gilmour, D. James, Bonete, María-José, Ferrer, Juan, Pire, Carmen, Esclapez, Julia, Rice, David W.
Format: Article
Language:English
Subjects:
Atoms
Biochemistry
Biological Sciences
Cellular biology
Crystal structure
Crystallization
Dehydrogenases
Dimers
Enzymes
Glucose Dehydrogenases - chemistry
Glucose Dehydrogenases - metabolism
Haloferax mediterranei
Haloferax mediterranei - enzymology
Hydrophobic and Hydrophilic Interactions
Ions
Molecular structure
Molecules
NADP - chemistry
NADP - metabolism
Potassium
Protein Binding
Protein Conformation
Proteins
Solvents
Solvents - chemistry
Water
X-rays
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Summary:The structure of glucose dehydrogenase from the extreme halophile Haloferax mediterranei has been solved at 1.6-Å resolution under crystallization conditions which closely mimic the "in vivo" intracellular environment. The decoration of the enzyme's surface with acidic residues is only partially neutralized by bound potassium counterions, which also appear to play a role in substrate binding. The surface shows the expected reduction in hydrophobic character, surprisingly not from changes associated with the loss of exposed hydrophobic residues but rather arising from a loss of lysines consistent with the genome wide-reduction of this residue in extreme halophiles. The structure reveals a highly ordered, multilayered solvation shell that can be seen to be organized into one dominant network covering much of the exposed surface accessible area to an extent not seen in almost any other protein structure solved. This finding is consistent with the requirement of the enzyme to form a protective shell in a dehydrating environment.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0508854103