4KYR: Structure of a product bound plant phosphatase

Starch is a water-insoluble, Glc-based biopolymer that is used for energy storage and is synthesized and degraded in a diurnal manner in plant leaves. Reversible phosphorylation is the only known natural starch modification and is required for starch degradation in planta. Critical to starch energy release is the activity of glucan phosphatases; however, the structural basis of dephosphorylation by glucan phosphatases is unknown. Here, we describe the structure of the Arabidopsis thaliana starch glucan phosphatase like sex four2 (LSF2) both with and without phospho-glucan product bound at 2.3A and 1.65A, respectively. LSF2 binds maltohexaose-phosphate using an aromatic channel within an extended phosphatase active site and positions maltohexaose in a C3-specific orientation, which we show is critical for the specific glucan phosphatase activity of LSF2 toward native Arabidopsis starch. However, unlike other starch binding enzymes, LSF2 does not possess a carbohydrate binding module domain. Instead we identify two additional glucan binding sites located within the core LSF2 phosphatase domain. This structure is the first of a glucan-bound glucan phosphatase and provides new insights into the molecular basis of this agriculturally and industrially relevant enzyme family as well as the unique mechanism of LSF2 catalysis, substrate specificity, and interaction with starch granules.
PDB ID: 4KYRDownload
MMDB ID: 112097
PDB Deposition Date: 2013/5/29
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Similar Structures:
Biological Unit for 4KYR: monomeric; determined by author and by software (PISA)
Molecular Components in 4KYR
Label Count Molecule
Protein (1 molecule)
Phosphoglucan Phosphatase Lsf2, Chloroplastic(Gene symbol: LSF2)
Molecule annotation
Chemicals (23 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB