Dynamics of starch granule biogenesis - the role of redox-regulated enzymes and low-affinity carbohydrate-binding modules

• Published in: Biocatalysis and biotransformation Vol. 28; no. 1; pp. 3 - 9
• Main Authors: Blennow, Andreas, Svensson, Birte
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Abingdon Informa UK Ltd. (Informa Healthcare, Taylor & Francis AS) 2010; Taylor & Francis
• Subjects: Bioconversions. Hemisynthesis; Biological and medical sciences; Biotechnology; enzyme affinity; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; redox regulation; Starch metabolism; starch phosphorylation; starch-binding domain; Starch metabolism; Phosphorylation; redox regulation; Starch; Enzyme; Metabolism; enzyme affinity; starch phosphorylation; Regulation(control); Dynamics; starch-binding domain; Affinity; Carbohydrate
• ISSN: 1024-2422; 1029-2446
• DOI: 10.3109/10242420903408211

Abstract The deposition and degradation of starch in plants is subject to extensive post-translational regulation. To permit degradation of B-type crystallites present in tuberous and leaf starch these starch types are phosphorylated by glucan, water dikinase (GWD). At the level of post-translational redox regulation, ADPglucose pyrophosphorylase, β-amylase (BAM1), limit dextrinase (LD), the starch phosphorylator GWD and the glucan phosphatase dual-specificity phosphatase 4 (DSP4), also named starch excess 4 (SEX4), are reductively activated in vitro. Redox screens now suggest the presence of a substantially more extensive and coordinated redox regulation involving a larger number of enzymes. Noticeably several of these enzymes contain a new type of low-affinity carbohydrate-binding module that we term a low-affinity starch-binding domain or LA-SBD. These are present in the CBM20, CBM45 and CBM53 families and can enable diurnal dynamics of starch-enzyme recognition. Such diurnal changes in starch binding have been indicated for the redox-regulated GWD and SEX4.