title: Phosphoglucan phosphatase function sheds light on starch degradation.
abstract: Phosphoglucan phosphatases are novel enzymes that remove phosphates from complex carbohydrates. In plants, these proteins are vital components in the remobilization of leaf starch at night. Breakdown of starch is initiated through reversible glucan phosphorylation to disrupt the semi-crystalline starch structure at the granule surface. The phosphoglucan phosphatases starch excess 4 (SEX4) and like-SEX4 2 (LSF2) dephosphorylate glucans to provide access for amylases that release maltose and glucose from starch. Another phosphatase, LSF1, is a putative inactive scaffold protein that may act as regulator of starch degradative enzymes at the granule surface. Absence of these phosphatases disrupts starch breakdown, resulting in plants accumulating excess starch. Here, we describe recent advances in understanding the biochemical and structural properties of each of these starch phosphatases.
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, AB, Canada.
authors.forename: Dylan M
authors.initials: DM
authors.lastname: Silver
authors.affiliation: Institute for Agricultural Sciences, ETH Zürich, Zürich, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kötting
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, AB, Canada. Electronic address: moorhead@ucalgary.ca.
authors.forename: Greg B G
authors.initials: GB
authors.lastname: Moorhead
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D005936:Glucans / Q000378:metabolism*; D008027:Light; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010710:Phosphates / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D018515:Plant Leaves / Q000378:metabolism; D016415:Sequence Alignment; D013213:Starch / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D005936:Glucans; D010710:Phosphates; D013213:Starch; D010744:Phosphoric Monoester Hydrolases
keywords: dual-specificity phosphatase; phosphoglucan phosphatase; phosphorylation; redox; starch degradation