ArticleProceedings of the National Academy of Sciences of the United States of America2014
Phosphoglucan-bound structure of starch phosphatase Starch Excess4 reveals the mechanism for C6 specificity.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 35 papers.
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Who cites it
35 citing papers in PubMed, 65 citations in OpenAlex.
- A structural perspective on α-glucan catabolism in oxygenic phototrophs.The Plant journal : for cell and molecular biology · 2026Review
- Noncatalytic functions of ISOAMYLASE 1 and 2 affect the proportion of insoluble and soluble α-polyglucans in maize.The Plant cell · 2025Article
- ZmSSRP1, transactivated by OPAQUE11, positively regulates starch biosynthesis in maize endosperm.Plant biotechnology journal · 2025Article
- Identification of Novel Inhibitors of Starch Excess 4 (SEX4).Life (Basel, Switzerland) · 2024Article
- Article
- Emerging Functions of Protein Tyrosine Phosphatases in Plants.International journal of molecular sciences · 2024Review
- The LIKE SEX FOUR 1-malate dehydrogenase complex functions as a scaffold to recruit β-amylase to promote starch degradation.The Plant cell · 2023Article
- Synergic action of an inserted carbohydrate-binding module in a glycoside hydrolase family 5 endoglucanase.Acta crystallographica. Section D, Structural biology · 2022Article
- Article
- A carbohydrate-binding family 48 module enables feruloyl esterase action on polymeric arabinoxylan.The Journal of biological chemistry · 2019Article
- LIKE SEX4 1 Acts as a β-Amylase-Binding Scaffold on Starch Granules during Starch Degradation.The Plant cell · 2019Article
- Brain Glycogen Structure and Its Associated Proteins: Past, Present and Future.Advances in neurobiology · 2019Review
- Oligomerization and carbohydrate binding of glucan phosphatases.Analytical biochemistry · 2018Article
- The unique evolution of the carbohydrate-binding module CBM20 in laforin.FEBS letters · 2018Article
- A comprehensive investigation of starch degradation process and identification of a transcriptional activator MabHLH6 during banana fruit ripening.Plant biotechnology journal · 2018Article
- Identification and analysis of OsttaDSP, a phosphoglucan phosphatase from Ostreococcus tauri.PloS one · 2018Article
- Functional Roles of Starch Binding Domains and Surface Binding Sites in Enzymes Involved in Starch Biosynthesis.Frontiers in plant science · 2018Review
- Homologs of PROTEIN TARGETING TO STARCH Control Starch Granule Initiation in Arabidopsis Leaves.The Plant cell · 2017Article
- Structure and Mechanism of Staphylococcus aureus TarS, the Wall Teichoic Acid β-glycosyltransferase Involved in Methicillin Resistance.PLoS pathogens · 2016Article
- Structural biology of glucan phosphatases from humans to plants.Current opinion in structural biology · 2016Review
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Authors and funding
8 authors at 2 institutions in 2 countries.
Funding
Abstract
Plants use the insoluble polyglucan starch as their primary glucose storage molecule. Reversible phosphorylation, at the C6 and C3 positions of glucose moieties, is the only known natural modification of starch and is the key regulatory mechanism controlling its diurnal breakdown in plant leaves. The glucan phosphatase Starch Excess4 (SEX4) is a position-specific starch phosphatase that is essential for reversible starch phosphorylation; its absence leads to a dramatic accumulation of starch in Arabidopsis, but the basis for its function is unknown. Here we describe the crystal structure of SEX4 bound to maltoheptaose and phosphate to a resolution of 1.65 Å. SEX4 binds maltoheptaose via a continuous binding pocket and active site that spans both the carbohydrate-binding module (CBM) and the dual-specificity phosphatase (DSP) domain. This extended interface is composed of aromatic and hydrophilic residues that form a specific glucan-interacting platform. SEX4 contains a uniquely adapted DSP active site that accommodates a glucan polymer and is responsible for positioning maltoheptaose in a C6-specific orientation. We identified two DSP domain residues that are responsible for SEX4 site-specific activity and, using these insights, we engineered a SEX4 double mutant that completely reversed specificity from the C6 to the C3 position. Our data demonstrate that the two domains act in consort, with the CBM primarily responsible for engaging glucan chains, whereas the DSP integrates them in the catalytic site for position-specific dephosphorylation. These data provide important insights into the structural basis of glucan phosphatase site-specific activity and open new avenues for their biotechnological utilization.
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