1EHA

CRYSTAL STRUCTURE OF GLYCOSYLTREHALOSE TREHALOHYDROLASE FROM SULFOLOBUS SOLFATARICUS

Summary for 1EHA

• Entry DOI: 10.2210/pdb1eha/pdb
• Related: 1EH9
• Descriptor: GLYCOSYLTREHALOSE TREHALOHYDROLASE (2 entities in total)
• Functional Keywords: trehalose, trehalohydrolase, sulfolobus solfataricus, alpha-beta barrel, calcium binding, covalent dimer, hydrolase
• Biological source: Sulfolobus solfataricus
• Cellular location: Cytoplasm : Q55088
• Total number of polymer chains: 1
• Total formula weight: 64737.72

Authors

Feese, M.D.,Kato, Y.,Tamada, T.,Kato, M.,Komeda, T.,Kobayashi, K.,Kuroki, R. (deposition date: 2000-02-19, release date: 2001-02-19, Last modification date: 2024-10-30)

Primary citation

Feese, M.D.,Kato, Y.,Tamada, T.,Kato, M.,Komeda, T.,Miura, Y.,Hirose, M.,Hondo, K.,Kobayashi, K.,Kuroki, R.
Crystal structure of glycosyltrehalose trehalohydrolase from the hyperthermophilic archaeum Sulfolobus solfataricus.
J.Mol.Biol., 301:451-464, 2000

PubMed Abstract: The crystal structure of glycosyltrehalose trehalohydrolase from the hyperthermophilic archaeum Sulfolobus solfataricus KM1 has been solved by multiple isomorphous replacement. The enzyme is an alpha-amylase (family 13) with unique exo-amylolytic activity for glycosyltrehalosides. It cleaves the alpha-1,4 glycosidic bond adjacent to the trehalose moiety to release trehalose and maltooligo saccharide. Unlike most other family 13 glycosidases, the enzyme does not require Ca(2+) for activity, and it contains an N-terminal extension of approximately 100 amino acid residues that is homologous to N-terminal domains found in many glycosidases that recognize branched oligosaccharides. Crystallography revealed the enzyme to exist as a homodimer covalently linked by an intermolecular disulfide bond at residue C298. The existence of the intermolecular disulfide bond was confirmed by biochemical analysis and mutagenesis. The N-terminal extension forms an independent domain connected to the catalytic domain by an extended linker. The functionally essential Ca(2+) binding site found in the B domain of alpha-amylases and many other family 13 glycosidases was found to be replaced by hydrophobic packing interactions. The enzyme also contains a very unusual excursion in the (beta/alpha)(8) barrel structure of the catalytic domain. This excursion originates from the bottom of the (beta/alpha)(8) barrel between helix 6 and strand 7, but folds upward in a distorted alpha-hairpin structure to form a part of the substrate binding cleft wall that is possibly critical for the enzyme's unique substrate selectivity. Participation of an alpha-beta loop in the formation of the substrate binding cleft is a novel feature that is not observed in other known (beta/alpha)(8) enzymes.

PubMed: 10926520
DOI: 10.1006/jmbi.2000.3977

Experimental method

X-RAY DIFFRACTION (3 Å)