STA11, a Chlamydomonas reinhardtii locus required for normal starch granule biogenesis, encodes disproportionating enzyme. Further evidence for a function of alpha-1,4 glucanotransferases during starch granule biosynthesis in green algae.
In Chlamydomonas reinhardtii, the presence of a defective STA11 locus results in significantly reduced granular starch deposition displaying major modifications in shape and structure. This defect simultaneously leads to the accumulation of linear malto-oligosaccharides (MOS). The mutants of STA11 were showed to lack D-enzyme, a plant alpha-1,4 glucanotransferase analogous to the Escherichia coli amylomaltase. We have cloned and characterized both the cDNA and gDNA corresponding to the C. reinhardtii D-enzyme. We now report allele-specific modifications of the D-enzyme gene in the mutants of STA11. These allele-specific modifications cosegregate with the corresponding sta11 mutations, thereby demonstrating that STA11 encodes D-enzyme. MOS production and starch accumulation were investigated during day and night cycles in wild-type and mutant C. reinhardtii cells. We demonstrate that in the algae MOS are produced during starch biosynthesis and degraded during the phases of net polysaccharide catabolism.
Unité de Glycobiologie Structurale et Fonctionnelle, Université des Sciences et Technologies de Lille, 59655 Villeneuve D'Ascq cedex, France.
Fabrice
F
Wattebled
Jean-Philippe
JP
Ral
David
D
Dauvillée
Alan M
AM
Myers
Martha G
MG
James
Ralf
R
Schlichting
Christoph
C
Giersch
Steven G
SG
Ball
Christophe
C
D'Hulst
D020418:Algal Proteins / Q000235:genetics / Q000378:metabolism; D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics*; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D006004:Glycogen Debranching Enzyme System / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009844:Oligosaccharides / Q000378:metabolism; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013213:Starch / Q000096:biosynthesis* / Q000378:metabolism
D020418:Algal Proteins; D018076:DNA, Complementary; D006004:Glycogen Debranching Enzyme System; D009844:Oligosaccharides; D012333:RNA, Messenger; C021705:maltooligosaccharides; D013213:Starch; D004247:DNA; C020569:4 alpha-glucanotransferase