Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
Yohei Ishibashi Last modified date:2019.06.14

Assistant Professor / Molecular Biosciences / Department of Bioscience and Biotechnology / Faculty of Agriculture

1. Yohei Ishibashi, Masaki Nagatomi, Nozomu Okino, Makoto Ito, Composition, localization, and metabolism of sphingolipids in thraustochytrids, 57th International Conference of the Bioscience of Lipids, 2016.09.
2. The Japanese Society of Carbohydrate Research, [URL].
3. 石橋 洋平, 永松 祐輔, 宮本 智文, 松永 尚之, 沖野 望, 山口 邦子, 伊東 信, The use of EGALC reveals the presence of a novel ether-linked phytol-containing digalactosylglycerolipid in the marine green alga, Ulva pertusa, SFG & JSCR 2014 Joint Annual Meeting, 2014.11, Galactosylglycerolipids (GGLs) and chlorophyll are characteristic components of chloroplast in photosynthetic organisms. Although chlorophyll is anchored to the thylakoid membrane by phytol (tetramethylhexadecenol), this isoprenoid alcohol has never been found as a constituent of GGLs. We here describe a novel GGL, in which phytol is linked to the glycerol backbone via an ether linkage (Ishibashi et al, 2014). This unique GGL was identified as an Alkaline-resistant and Endogalactosylceramidase (EGALC)-sensitive GlycoLipid (AEGL) in the marine green alga, Ulva pertusa. EGALC is an enzyme that is capable of cleaving the β-glycosidic linkage between R-Galα/β1-6Gal and the lipid moiety, thereby releasing intact galactooligosaccharide from glycolipids. The specificity of EGALC is very high for the sugar moiety, but relatively wide for the lipid moiety, i.e., it hydrolyzes GGLs as well as glycosphingolipids (GSLs). EGALC also catalyzes transglycosylation reaction, in which the intact sugar chains are transferred from GSLs/GGLs to the primary hydroxyl group of various 1-alkanols to generate neoglycoconjugates. We previously developed a sensitive and reliable method to detect GSLs/GGLs that share the R-Galα/β1-6Galβ1- structure, using the transglycosylation reaction of EGALC. The use of EGALC revealed that AEGLs were ubiquitously distributed in not only green, but also red and brown marine algae; however, they were rarely detected in terrestrial plants, eukaryotic phytoplankton, or cyanobacteria. The structure of U. pertusa AEGL was determined following its purification to 1-O-phytyl-3-O-Galα1-6Galβ1-sn-glycerol by mass spectrometric and nuclear magnetic resonance analyses. To the best of our knowledge, this is the first study to identify a phytol-containing GGL that may be present in the thylakoid membrane of chloroplasts in marine algae. Since GGLs have been shown to possess important roles in the organization and stabilization of the thylakoid membrane, the novel GGL, AEGL, could have a specific role in photosynthesis in marine algae..