title: The primitive rhodophyte Cyanidioschyzon merolae contains a semiamylopectin-type, but not an amylose-type, alpha-glucan.
abstract: 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.
authors.affiliation: School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392 Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Hirabaru
authors.forename: Asako
authors.initials: A
authors.lastname: Izumo
authors.forename: Shoko
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Yukie
authors.initials: Y
authors.lastname: Tadokoro
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shimonaga
authors.forename: Mai
authors.initials: M
authors.lastname: Konishi
authors.forename: Mayumi
authors.initials: M
authors.lastname: Yoshida
authors.forename: Naoko
authors.initials: N
authors.lastname: Fujita
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Masaki
authors.initials: M
authors.lastname: Yoshida
authors.forename: Tsuneyoshi
authors.initials: T
authors.lastname: Kuroiwa
authors.forename: Mikio
authors.initials: M
authors.lastname: Tsuzuki
mesh_terms: D000687:Amylopectin / Q000737:chemistry*; D000688:Amylose; D002850:Chromatography, Gel; D057075:Enzyme Assays; D005936:Glucans / Q000737:chemistry*; D000461:Rhodophyta / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D024941:Starch Phosphorylase / Q000032:analysis; D013214:Starch Synthase
chemical_list: D005936:Glucans; D000688:Amylose; D000687:Amylopectin; D024941:Starch Phosphorylase; D013214:Starch Synthase