6LCK

TtGalA, alpha-galactosidase from Thermus thermophilus in complex with p-nitrophenyl alpha-D-galactopyranoside (alpha-NPG)

Summary for 6LCK

• Entry DOI: 10.2210/pdb6lck/pdb
• Descriptor: Alpha-galactosidase, 4-nitrophenyl alpha-D-galactopyranoside (2 entities in total)
• Functional Keywords: alpha-galactosidase, hexamer assembly, substrate specificity, thermostable, stachyose, hydrolase
• Biological source: Thermus thermophilus (strain HB8 / ATCC 27634 / DSM 579)
• Total number of polymer chains: 3
• Total formula weight: 162862.67

Authors

Chen, S.C.,Hsu, C.H. (deposition date: 2019-11-19, release date: 2020-07-01, Last modification date: 2024-04-03)

Primary citation

Chen, S.C.,Wu, S.P.,Chang, Y.Y.,Hwang, T.S.,Lee, T.H.,Hsu, C.H.
Crystal Structure of alpha-Galactosidase fromThermus thermophilus: Insight into Hexamer Assembly and Substrate Specificity.
J.Agric.Food Chem., 68:6161-6169, 2020

PubMed Abstract: α-Galactosidase catalyzes the hydrolysis of a terminal α-galactose residue in galacto-oligosaccharides and has potential in various industrial applications and food processing. We determined the crystal structures of α-galactosidase from the thermophilic microorganism (TtGalA) and its complexes with pNPGal and stachyose. The monomer folds into an N-terminal domain, a catalytic (β/α) barrel domain, and a C-terminal domain. The domain organization is similar to that of the other family of 36 α-galactosidases, but TtGalA presents a cagelike hexamer. Structural analysis shows that oligomerization may be a key factor for the thermal adaption of TtGalA. The structure of TtGalA complexed with stachyose reveals only the existence of one -1 subsite and one +1 subsite in the active site. Structural comparison of the stachyose-bound complexes of TtGalA and GsAgaA, a tetrameric enzyme with four subsites, suggests evolutionary divergence of substrate specificity within the GH36 family of α-galactosidases. To the best of our knowledge, the crystal structure of TtGalA is the first report of a quaternary structure as a hexameric assembly in the α-galactosidase family.

PubMed: 32390413
DOI: 10.1021/acs.jafc.0c00871

Experimental method

X-RAY DIFFRACTION (2.85 Å)