2R68: Complex Structure Of Sucrose Phosphate Synthase (sps)-s6p Of Halothermothrix Orenii

Sucrose phosphate synthase (SPS) catalyzes the transfer of a glycosyl group from an activated donor sugar, such as uridine diphosphate glucose (UDP-Glc), to a saccharide acceptor D-fructose 6-phosphate (F6P), resulting in the formation of UDP and D-sucrose-6'-phosphate (S6P). This is a central regulatory process in the production of sucrose in plants, cyanobacteria, and proteobacteria. Here, we report the crystal structure of SPS from the nonphotosynthetic bacterium Halothermothrix orenii and its complexes with the substrate F6P and the product S6P. SPS has two distinct Rossmann-fold domains with a large substrate binding cleft at the interdomain interface. Structures of two complexes show that both the substrate F6P and the product S6P bind to the A-domain of SPS. Based on comparative analysis of the SPS structure with other related enzymes, the donor substrate, nucleotide diphosphate glucose, binds to the B-domain of SPS. Furthermore, we propose a mechanism of catalysis by H. orenii SPS. Our findings indicate that SPS from H. orenii may represent a valid model for the catalytic domain of plant SPSs and thus may provide useful insight into the reaction mechanism of the plant enzyme.
PDB ID: 2R68Download
MMDB ID: 64825
PDB Deposition Date: 2007/9/5
Updated in MMDB: 2012/12
Experimental Method:
x-ray diffraction
Resolution: 2.4  Å
Source Organism:
Similar Structures:
Biological Unit for 2R68: monomeric; determined by author and by software (PISA)
Molecular Components in 2R68
Label Count Molecule
Protein (1 molecule)
Glycosyl Transferase, Group 1
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

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