6SED

Cold-adapted beta-D-galactosidase from Arthrobacter sp. 32cB in complex with galactose

Summary for 6SED

• Entry DOI: 10.2210/pdb6sed/pdb
• Descriptor: Beta-galactosidase, beta-D-galactopyranose, ACETATE ION, ... (7 entities in total)
• Functional Keywords: galactosidase, cold-adapted, psychrophilic, dimeric, hydrolase
• Biological source: Arthrobacter sp. 32cB
• Total number of polymer chains: 1
• Total formula weight: 110759.05

Authors

Rutkiewicz, M.,Bujacz, A.,Kaminska, P.,Bujacz, G. (deposition date: 2019-07-29, release date: 2019-09-11, Last modification date: 2024-01-24)

Primary citation

Rutkiewicz, M.,Bujacz, A.,Wanarska, M.,Wierzbicka-Wos, A.,Cieslinski, H.
Active Site Architecture and Reaction Mechanism Determination of Cold Adapted beta-d-galactosidase fromArthrobactersp. 32cB.
Int J Mol Sci, 20:-, 2019

PubMed Abstract: βDG is a dimeric, cold-adapted β-d-galactosidase that exhibits high hydrolytic and transglycosylation activity. A series of crystal structures of its wild form, as well as its βDG_E441Q mutein complexes with ligands were obtained in order to describe the mode of its action. The βDG_E441Q mutein is an inactive form of the enzyme designed to enable observation of enzyme interaction with its substrate. The resulting three-dimensional structures of complexes: βDG_E441Q/LACs and βDG/IPTG (ligand bound in shallow mode) and structures of complexes βDG_E441Q/LACd, βDG/ONPG (ligands bound in deep mode), and galactose βDG/GAL and their analysis enabled structural characterization of the hydrolysis reaction mechanism. Furthermore, comparative analysis with mesophilic analogs revealed the most striking differences in catalysis mechanisms. The key role in substrate transfer from shallow to deep binding mode involves rotation of the F581 side chain. It is worth noting that the 10-aa loop restricting access to the active site in mesophilic GH2 βDGs, in βDG is moved outward. This facilitates access of substrate to active site. Such a permanent exposure of the entrance to the active site may be a key factor for improved turnover rate of the cold adapted enzyme and thus a structural feature related to its cold adaptation.

PubMed: 31484304
DOI: 10.3390/ijms20174301

Experimental method

X-RAY DIFFRACTION (2.233 Å)