1M53
CRYSTAL STRUCTURE OF ISOMALTULOSE SYNTHASE (PALI) FROM KLEBSIELLA SP. LX3
Summary for 1M53
| Entry DOI | 10.2210/pdb1m53/pdb |
| Related | 1G5A 1UOK |
| Descriptor | Isomaltulose Synthase (2 entities in total) |
| Functional Keywords | klebsiella sp. lx3, isomaltulose synthase, sucrose isomerization, isomerase |
| Biological source | Klebsiella sp. LX3 |
| Total number of polymer chains | 1 |
| Total formula weight | 67251.80 |
| Authors | Li, N.,Swaminathan, K. (deposition date: 2002-07-08, release date: 2003-07-08, Last modification date: 2023-10-25) |
| Primary citation | Zhang, D.,Li, N.,Lok, S.M.,Zhang, L.-H.,Swaminathan, K. Isomaltulose synthase (PalI) of Klebsiella sp. LX3. Crystal structure and implication of mechanism J.Biol.Chem., 278:35428-35434, 2003 Cited by PubMed Abstract: Isomaltulose synthase from Klebsiella sp. LX3 (PalI, EC 5.4.99.11) catalyzes the isomerization of sucrose to produce isomaltulose (alpha-D-glucosylpyranosyl-1,6-D-fructofuranose) and trehalulose (alpha-D-glucosylpyranosyl-1,1-d-fructofuranose). The PalI structure, solved at 2.2-A resolution with an R-factor of 19.4% and Rfree of 24.2%, consists of three domains: an N-terminal catalytic (beta/alpha)8 domain, a subdomain between N beta 3 and N alpha 3, and a C-terminal domain having seven beta-strands. The active site architecture of PalI is identical to that of other glycoside hydrolase family 13 members, suggesting a similar mechanism in substrate binding and hydrolysis. However, a unique RLDRD motif in the proximity of the active site has been identified and shown biochemically to be responsible for sucrose isomerization. A two-step reaction mechanism for hydrolysis and isomerization, which occurs in the same pocket is proposed based on both the structural and biochemical data. Selected C-terminal truncations have been shown to reduce and even abolish the enzyme activity, consistent with the predicted role of the C-terminal residues in the maintenance of enzyme conformation and active site topology. PubMed: 12819210DOI: 10.1074/jbc.M302616200 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.2 Å) |
Structure validation
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