1G5A

AMYLOSUCRASE FROM NEISSERIA POLYSACCHAREA

Summary for 1G5A

• Entry DOI: 10.2210/pdb1g5a/pdb
• Descriptor: AMYLOSUCRASE, SODIUM ION, 2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL, ... (5 entities in total)
• Functional Keywords: glycosyltransferase, glycoside hydrolase, (beta-alpha)8 barrel, transferase
• Biological source: Neisseria polysaccharea
• Cellular location: Secreted: Q9ZEU2
• Total number of polymer chains: 1
• Total formula weight: 71947.52

Authors

Skov, L.K.,Mirza, O.,Henriksen, A.,De Montalk, G.P.,Remaud-Simeon, M.,Sarcabal, P.,Willemot, R.-M.,Monsan, P.,Gajhede, M. (deposition date: 2000-10-31, release date: 2001-10-31, Last modification date: 2024-02-07)

Primary citation

Skov, L.K.,Mirza, O.,Henriksen, A.,De Montalk, G.P.,Remaud-Simeon, M.,Sarcabal, P.,Willemot, R.M.,Monsan, P.,Gajhede, M.
Amylosucrase, A Glucan-synthesizing Enzyme from the alpha-Amylase Family
J.Biol.Chem., 276:25273-25278, 2001

PubMed Abstract: Amylosucrase (E.C. 2.4.1.4) is a member of Family 13 of the glycoside hydrolases (the alpha-amylases), although its biological function is the synthesis of amylose-like polymers from sucrose. The structure of amylosucrase from Neisseria polysaccharea is divided into five domains: an all helical N-terminal domain that is not similar to any known fold, a (beta/alpha)(8)-barrel A-domain, B- and B'-domains displaying alpha/beta-structure, and a C-terminal eight-stranded beta-sheet domain. In contrast to other Family 13 hydrolases that have the active site in the bottom of a large cleft, the active site of amylosucrase is at the bottom of a pocket at the molecular surface. A substrate binding site resembling the amylase 2 subsite is not found in amylosucrase. The site is blocked by a salt bridge between residues in the second and eight loops of the (beta/alpha)(8)-barrel. The result is an exo-acting enzyme. Loop 7 in the amylosucrase barrel is prolonged compared with the loop structure found in other hydrolases, and this insertion (forming domain B') is suggested to be important for the polymer synthase activity of the enzyme. The topology of the B'-domain creates an active site entrance with several ravines in the molecular surface that could be used specifically by the substrates/products (sucrose, glucan polymer, and fructose) that have to get in and out of the active site pocket.

PubMed: 11306569
DOI: 10.1074/jbc.M010998200

Experimental method

X-RAY DIFFRACTION (1.4 Å)