26WE

Crystal structure of L-galactose dehydrogenase M212Q mutant in complex with L-glucose and NADP+

Summary for 26WE

• Entry DOI: 10.2210/pdb26we/pdb
• Descriptor: L-galactose dehydrogenase, beta-L-glucopyranose, NADP NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE, ... (5 entities in total)
• Functional Keywords: complex, oxidoreductase
• Biological source: Luteolibacter sp. LG18
• Total number of polymer chains: 2
• Total formula weight: 77843.07

Authors

Ito, C.,Obara, N.,Kawashita, K.,Takenoya, M.,Kim, M.,Ito, S.,Sasaki, Y.,Yajima, S. (deposition date: 2026-05-18, release date: 2026-10-28)

Primary citation

Obara, N.,Ito, C.,Kawashita, K.,Takenoya, M.,Kim, M.,Ito, S.,Sasaki, Y.,Nakamura, A.,Yajima, S.
A single amino acid mutation alters substrate specificity towards l-glucose in a bacterial l-galactose dehydrogenase.
Biochem Biophys Rep, 48:102819-102819, 2026

PubMed Abstract: Structure-based mutagenesis was performed to modify the substrate specificity of bacterial l-galactose dehydrogenase from sp. strain LG18, which also exhibits intrinsic l-glucose dehydrogenase activity. Based on previously reported crystal structures of the enzyme in ternary complex with l-galactose or l-glucose and NADP, an M212Q mutant was generated and found to exhibit a pronounced preference for l-glucose. Kinetic analysis showed that the M212Q mutant displayed an approximately 20-fold higher / value for l-glucose than for l-galactose. To elucidate the structural basis of this altered specificity, the X-ray crystal structure of the M212Q mutant complexed with l-glucose and NADP was determined. Substitution of Met212 with Gln is assumed to disrupt the hydrophobic environment between the residue and the substrates, which may prevent proper binding of l-galactose and resulting in an approximately 350-fold increase in compared with the wild type. In contrast, in the l-glucose-bound M212Q structure, a compensatory hydrogen bond is formed between the equatorial 4-OH group of l-glucose and Gln212, stabilizing substrate binding and reducing the value to approximately one-quarter of that of the wild type. Furthermore, a BLAST search with Lu-LGDH as a query resulted that homologs containing the glutamine residue at the corresponding position as well as other conserved catalytic and substrate-binding residues were found. With emerging studies on l-glucose biology, these results may contribute to enzymatic approaches for detecting the enzymes acting toward l-glucose, which is generally considered absent in nature.

PubMed: 42876446
DOI: 10.1016/j.bbrep.2026.102819

Experimental method

X-RAY DIFFRACTION (1.76 Å)