title: Subcellular distribution of central carbohydrate metabolism pathways in the red alga Cyanidioschyzon merolae.
abstract: Comprehensive subcellular localization analysis revealed that the subcellular distribution of carbohydrate metabolic pathways in the red alga Cyanidioschyzon is essentially identical with that in Arabidopsis , except the lack of transaldolase. In plants, the glycolysis and oxidative pentose phosphate pathways (oxPPP) are located in both cytosol and plastids. However, in algae, particularly red algae, the subcellular localization of enzymes involved in carbon metabolism is unclear. Here, we identified and examined the localization of enzymes related to glycolysis, oxPPP, and tricarboxylic acid (TCA) and Calvin-Benson cycles in the red alga Cyanidioschyzon merolae. A gene encoding transaldolase of the oxPPP was not found in the C. merolae genome, and no transaldolase activity was detected in cellular extracts. The subcellular localization of 65 carbon metabolic enzymes tagged with green fluorescent protein or hemagglutinin was examined in C. merolae cells. As expected, TCA and Calvin-Benson cycle enzymes were localized to mitochondria and plastids, respectively. The analyses also revealed that the cytosol contains the entire glycolytic pathway and partial oxPPP, whereas the plastid contains a partial glycolytic pathway and complete oxPPP, with the exception of transaldolase. Together, these results suggest that the subcellular distribution of carbohydrate metabolic pathways in C. merolae is essentially identical with that reported in the photosynthetic tissue of Arabidopsis thaliana; however, it appears that substrates typically utilized by transaldolase are consumed by glycolytic enzymes in the plastidic oxPPP of C. merolae.
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902, Japan, moripoly@bio.c.u-tokyo.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Moriyama
authors.forename: Kenta
authors.initials: K
authors.lastname: Sakurai
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Sekine
authors.forename: Naoki
authors.initials: N
authors.lastname: Sato
mesh_terms: D050260:Carbohydrate Metabolism; D049452:Green Fluorescent Proteins; D053858:Metabolic Networks and Pathways; D000461:Rhodophyta / Q000201:enzymology* / Q000235:genetics
chemical_list: D049452:Green Fluorescent Proteins