2WPG

Sucrose Hydrolase

Summary for 2WPG

• Entry DOI: 10.2210/pdb2wpg/pdb
• Descriptor: AMYLOSUCRASE OR ALPHA AMYLASE (2 entities in total)
• Functional Keywords: hydrolase, enzyme, sucrose hydrolysis, glycosyl hydrolase family 13
• Biological source: XANTHOMONAS CAMPESTRIS PV. CAMPESTRIS
• Total number of polymer chains: 1
• Total formula weight: 69362.91

Authors

Champion, E.,Remaud-Simeon, M.,Skov, L.K.,Kastrup, J.S.,Gajhede, M.,Mirza, O. (deposition date: 2009-08-06, release date: 2009-11-24, Last modification date: 2023-12-20)

Primary citation

Champion, E.,Remaud-Simeon, M.,Skov, L.K.,Kastrup, J.S.,Gajhede, M.,Mirza, O.
The Apo Structure of Sucrose Hydrolase from Xanthomonas Campestris Pv. Campestris Shows an Open Active-Site Groove
Acta Crystallogr.,Sect.D, 65:1309-, 2009

PubMed Abstract: Glycoside hydrolase family 13 (GH-13) mainly contains starch-degrading or starch-modifying enzymes. Sucrose hydrolases utilize sucrose instead of amylose as the primary glucosyl donor. Here, the catalytic properties and X-ray structure of sucrose hydrolase from Xanthomonas campestris pv. campestris are reported. Sucrose hydrolysis catalyzed by the enzyme follows Michaelis-Menten kinetics, with a K(m) of 60.7 mM and a k(cat) of 21.7 s(-1). The structure of the enzyme was solved at a resolution of 1.9 A in the resting state with an empty active site. This represents the first apo structure from subfamily 4 of GH-13. Comparisons with structures of the highly similar sucrose hydrolase from X. axonopodis pv. glycines most notably showed that residues Arg516 and Asp138, which form a salt bridge in the X. axonopodis sucrose complex and define part of the subsite -1 glucosyl-binding determinants, are not engaged in salt-bridge formation in the resting X. campestris enzyme. In the absence of the salt bridge an opening is created which gives access to subsite -1 from the ;nonreducing' end. Binding of the glucosyl moiety in subsite -1 is therefore likely to induce changes in the conformation of the active-site cleft of the X. campestris enzyme. These changes lead to salt-bridge formation that shortens the groove. Additionally, this finding has implications for understanding the molecular mechanism of the closely related subfamily 4 glucosyl transferase amylosucrase, as it indicates that sucrose could enter the active site from the ;nonreducing' end during the glucan-elongation cycle.

PubMed: 19966417
DOI: 10.1107/S0907444909040311

Experimental method

X-RAY DIFFRACTION (1.9 Å)