Structural elucidation of novel phosphocholine-containing glycosylinositol-phosphoceramides in filamentous fungi and their induction of cell death of cultured rice cells.
Novel ZGLs (zwitterionic glycosphingolipids) have been found in and extracted from the mycelia of filamentous fungi ( Acremonium sp.) isolated from soil. Five ZGLs (ZGL1-ZGL5) were structurally elucidated by sugar compositional analysis, methylation analysis, periodate oxidation, matrix-assisted laser-desorption ionization-time-of-flight MS, (1)H-NMR spectroscopy and fast-atom bombardment MS. Their chemical structures were as follows: GlcN(alpha1-2)Ins1-P-1Cer (ZGL1), Man(alpha1-6)GlcN(alpha1-2)Ins1-P-1Cer (ZGL2), Man(alpha1-6)Man(alpha1-6)GlcN(alpha1-2)Ins1-P-1Cer (ZGL3), PC-->6Man(alpha1-6)GlcN(alpha1-2)Ins1- P -1Cer (ZGL4), and PC-->6Man(alpha1-6)Man(alpha1-6)GlcN(alpha1-2)Ins1-P-1Cer (ZGL5) (where Cer is ceramide and PC is phosphocholine). In addition, one acidic glycosphingolipid, which was the precursor of ZGLs, was also characterized as inositol-phosphoceramide. The core structure of the ZGLs, GlcN(alpha1-2)Ins1- P, is rather different from those found in other fungi, such as Man(alpha1-2)Ins1- P and Man(alpha1-6)Ins1- P. Interestingly, the terminal mannose residue of ZGL4 and ZGL5 was modified further with a PC group. The presence of PC-containing glycosylinositol-phosphoceramides has not been reported previously in any organism. The ceramide constituents of both ZGLs and acidic glycosphingolipid were essentially the same, and consisted of a 4-hydroxyoctadecasphinganine (phytosphingosine) as the sole sphingoid base and 2-hydroxytetracosanoic acid (>90%) as the major fatty acid. ZGLs were found to cause cell death in suspensions of cultured rice cells. The cell death-inducing activity of ZGLs is probably due to the characteristic glycan moiety of Man(alpha1-6)GlcN, and PC-containing ZGLs had high activity. This study is the first to demonstrate that fungal glycosylinositol-phosphoceramides induce cell death in cultured rice cells.
Graduate School of Biostudies, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan. kaoki@lif.kyoto-u.ac.jp
Kazuhiro
K
Aoki
Ryosuke
R
Uchiyama
Saki
S
Itonori
Mutsumi
M
Sugita
Fang-Sik
FS
Che
Akira
A
Isogai
Noriyasu
N
Hada
Junko
J
Hada
Tadahiro
T
Takeda
Hidehiko
H
Kumagai
Kenji
K
Yamamoto
D020384:Acidic Glycosphingolipids / Q000737:chemistry; D000164:Acremonium / Q000737:chemistry; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000032:analysis / Q000737:chemistry; D016923:Cell Death; D002478:Cells, Cultured; D002518:Ceramides / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*; D005227:Fatty Acids / Q000032:analysis; D005658:Fungi / Q000737:chemistry*; D017261:Glycosylphosphatidylinositols / Q000032:analysis*; D008969:Molecular Sequence Data; D012275:Oryza / Q000166:cytology / Q000187:drug effects*; D010767:Phosphorylcholine / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D020384:Acidic Glycosphingolipids; D002241:Carbohydrates; D002518:Ceramides; D005227:Fatty Acids; D017261:Glycosylphosphatidylinositols; D010767:Phosphorylcholine