The primitive rhodophyte Cyanidioschyzon merolae contains a semiamylopectin-type, but not an amylose-type, alpha-glucan.
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.
Hirabaru
Chika
C
School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo, 192-0392 Japan.
Izumo
Asako
A
Fujiwara
Shoko
S
Tadokoro
Yukie
Y
Shimonaga
Takahiro
T
Konishi
Mai
M
Yoshida
Mayumi
M
Fujita
Naoko
N
Nakamura
Yasunori
Y
Yoshida
Masaki
M
Kuroiwa
Tsuneyoshi
T
Tsuzuki
Mikio
M
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
D005936:Glucans; D000688:Amylose; D000687:Amylopectin; D024941:Starch Phosphorylase; D013214:Starch Synthase