Storage, Photosynthesis, and Growth: The Conditional Nature of Mutations Affecting Starch Synthesis and Structure in Chlamydomonas

Libessart, Nathalie; Maddelein, Marie‐Lise; Koornhuyse, Nathalie van den; Decq, André; Delrue, Brigitte; Mouille, Grégory; d’Hulst, Christophe; Ball, Steven

doi:10.2307/3870089

Cited by 48 publications

(66 citation statements)

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“…We were surprised to find a modification of amylopectin chain-length distribution. The latter consisted of a relative increase of very small chains that could easily be distinguished from similar distributions witnessed in other mutant amylopectin structures (Fontaine et al, 1993;Libessart et al, 1995). This surprising change correlated with an alteration in granule size morphology and crystallinity.…”

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confidence: 90%

Biochemical Characterization of the Chlamydomonas reinhardtii α-1,4 Glucanotransferase Supports a Direct Function in Amylopectin Biosynthesis1

et al. 1999

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Plant ␣-1,4 glucanotransferases (disproportionating enzymes, or D-enzymes) transfer glucan chains among oligosaccharides with the concomitant release of glucose (Glc). Analysis of Chlamydomonas reinhardtii sta11-1 mutants revealed a correlation between a D-enzyme deficiency and specific alterations in amylopectin structure and starch biosynthesis, thereby suggesting previously unknown biosynthetic functions. This study characterized the biochemical activities of the ␣-1,4 glucanotransferase that is deficient in sta11-1 mutants. The enzyme exhibited the glucan transfer and Glc production activities that define D-enzymes. D-enzyme also transferred glucans among the outer chains of amylopectin (using the polysaccharide chains as both donor and acceptor) and from malto-oligosaccharides into the outer chains of either amylopectin or glycogen. In contrast to transfer among oligosaccharides, which occurs readily with maltotriose, transfer into polysaccharide required longer donor molecules. All three enzymatic activities, evolution of Glc from oligosaccharides, glucan transfer from oligosaccharides into polysaccharides, and transfer among polysaccharide outer chains, were evident in a single 62-kD band. Absence of all three activities co-segregated with the sta11-1 mutation, which is known to cause abnormal accumulation of oligosaccharides at the expense of starch. To explain these data we propose that D-enzymes function directly in building the amylopectin structure.In plants, the only ␣-1,4 glucanotransferases reported to be present at the time of starch synthesis are collectively called D-enzymes (Peat et al., 1956;Takaha et al., 1993). D-enzymes act on soluble oligosaccharides at least three Glc residues long (maltotriose) and disproportionate them into oligosaccharides of various lengths at the expense of Glc formation. In such a reaction an ␣-1,4 linkage is cleaved from a donor unbranched oligosaccharide of at least three Glc residues, and the resulting chain segment is transferred to another acceptor glucan, creating a novel ␣-1,4 linkage. Maltosyl residues are often transferred as a result of D-enzyme action, but maltose itself is not a product of the reaction. However, both Glc and maltose can be used as acceptors (Jones and Whelan, 1969). It is known that in Arabidopsis leaves, D-enzyme is the major maltotriosemetabolizing enzyme present (Lin and Preiss, 1988;Zeeman et al., 1998). The presence of this activity during potato tuber development has led investigators to suggest that D-enzyme might be required for some specific aspect of starch biosynthesis (Takaha et al., 1993). Like a few other glucanotransferases, such as branching enzyme (Takaha et al., 1996a), D-enzyme has been recently shown to lead to the formation of cyclic compounds after prolonged incubation of both amylose and amylopectin with high amounts of pure activity (Takaha et al., 1996b(Takaha et al., , 1998. It is not known if this property relates to the physiological function of this enzyme. D-enzyme is believed to be part of the starch degra...

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Biochemical Characterization of the Chlamydomonas reinhardtii α-1,4 Glucanotransferase Supports a Direct Function in Amylopectin Biosynthesis1

et al. 1999

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“…Diatoms are not necessarily better at storing carbohydrates than green algae. For example, C. reinhardtii has quite an impressive ability to accumulate starch [71]. However, it may be important to consider the relative energetics involved in accessing a soluble carbohydrate (chrysolaminarin) stored in a vacuole versus an insoluble form (starch) stored in the chloroplast.…”

Section: Compartmentation and Carbon Metabolism In Diatomsmentioning

confidence: 99%

The place of diatoms in the biofuels industry

et al. 2012

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“…Chlamydomonas reinhardtii is an alga model for studying starch synthesis and it is able to synthesize either transient or storage starch, depending on growth in the presence or absence of nitrogen, respectively (15,16). Under nitrogen starvation conditions, Chlamydomonas strains carrying mutations at either the STA7 and STA8 loci display phenotypes similar to that of the respective ISA1 and ISA2 mutants observed in the cereal species (7,17).…”

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Crystal Structure of the Chlamydomonas Starch Debranching Enzyme Isoamylase ISA1 Reveals Insights into the Mechanism of Branch Trimming and Complex Assembly

Sim¹,

Beeren²,

Findinier³

et al. 2014

Journal of Biological Chemistry

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Background:The ISA1⅐ISA2 isoamylase complex is involved in starch synthesis. Results: The ISA1 homodimer from the green algae Chlamydomonas is functional without ISA2 and its crystal structure is described. Conclusion: The ISA1 structure reveals potential substrate recognition sites and explains its low selectivity toward tightly spaced branches. Significance: Structural conservation with plant ISA1 suggests it may be a useful model for studying branch trimming.

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Storage, Photosynthesis, and Growth: The Conditional Nature of Mutations Affecting Starch Synthesis and Structure in Chlamydomonas

Cited by 48 publications

References 17 publications

Biochemical Characterization of the Chlamydomonas reinhardtii α-1,4 Glucanotransferase Supports a Direct Function in Amylopectin Biosynthesis1

Biochemical Characterization of the Chlamydomonas reinhardtii α-1,4 Glucanotransferase Supports a Direct Function in Amylopectin Biosynthesis1

The place of diatoms in the biofuels industry

Crystal Structure of the Chlamydomonas Starch Debranching Enzyme Isoamylase ISA1 Reveals Insights into the Mechanism of Branch Trimming and Complex Assembly

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