Journal Article

The primitive rhodophyte <i>Cyanidioschyzon merolae</i> contains a semiamylopectin-type, but not an amylose-type, α-glucan

Chika Hirabaru, Asako Izumo, Shoko Fujiwara, Yukie Tadokoro, Takahiro Shimonaga, Mai Konishi, Mayumi Yoshida, Naoko Fujita, Yasunori Nakamura, Masaki Yoshida, Tsuneyoshi Kuroiwa and Mikio Tsuzuki

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 51, issue 5, pages 682-693
Published in print May 2010 | ISSN: 0032-0781
Published online April 2010 | e-ISSN: 1471-9053 | DOI:
The primitive rhodophyte Cyanidioschyzon merolae contains a semiamylopectin-type, but not an amylose-type, α-glucan

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The storage glucans of Cyanidioschyzon merolae [clade L-1 (cyanidian algae), order Porphyridiales, subclass Bangiophycidae], which is considered to be one of the most primitive rhodophytes, were analyzed to understand the early evolution of the glucan structure in the Rhodophyta. Chain-length distribution analysis of the glucans of cyanidian algae demonstrated that while the glucans of Cyanidium caldarium and Galdieria sulphuraria are of the glycogen type, those of C. merolae are of the semiamylopectin type, as in other lineages of the Rhodophyta. Gel permeation chromatography, however, showed that the glucans of C. merolae do not include amylose, being different from those of other Bangiophycidae species. Identification by MALDI–TOF-MS and enzyme assaying of glucan granule-bound proteins indicated that phosphorylase, but not starch synthase, is included. Thus, C. merolae has an unusual glucan and bound-protein composition for the Bangiophycidae, appearing to be a member of the Florideophycidae. The finding that the alga does not contain amylose or the related enzyme, granule-bound starch synthase, is, however, consistent with previously reported results of molecular phylogenetic analysis of starch synthases. Our results support an evolutionary scenario defined by the loss of starch and reversion to glycogen synthesis during the evolution of cyanidian algae, and suggest the possibility that a C. merolae-like primitive rhodophyte might have evolved into the Florideophycidae.

Keywords: Amylose; Cyanidioschyzon; Floridean starch; Glycogen; Starch synthase; Semiamylopectin

Journal Article.  6434 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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