GfsA is a β1,5-galactofuranosyltransferase involved in the biosynthesis of the galactofuran side chain of fungal-type galactomannan in Aspergillus fumigatus

Yukako Katafuchi, Qiushi Li, Yutaka Tanaka, Saki Shinozuka, Yohei Kawamitsu, Minoru Izumi, Keisuke Ekino, Keiji Mizuki, Kaoru Takegawa, Nobuyuki Shibata, Masatoshi Goto, Yoshiyuki Nomura, Kazuyoshi Ohta, Takuji Oka

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Previously, we reported that GfsA is a novel galactofuranosyltransferase involved in the biosynthesis of O-glycan, the proper maintenance of fungal morphology, the formation of conidia and anti-fungal resistance in Aspergillus nidulans and A. fumigatus (Komachi Y et al., 2013. GfsA encodes a novel galactofuranosyltransferase involved in biosynthesis of galactofuranose antigen of O-glycan in Aspergillus nidulans and Aspergillus fumigatus. Mol. Microbiol. 90:1054-1073). In the present paper, to gain an in depth-understanding of the enzymatic functions of GfsA in A. fumigatus (AfGfsA), we established an in vitro assay to measure galactofuranosyltransferase activity using purified AfGfsA, UDP-α-D-galactofuranose as a sugar donor, and p-nitrophenyl-β-Dgalactofuranoside as an acceptor substrate. LC/MS, 1H-NMR and methylation analyses of the enzymatic products of AfGfsA revealed that this protein has the ability to transfer galactofuranose to the C-5 position of the β-galactofuranose residue via a β-linkage. AfGfsA requires a divalent cation of manganese for maximal activity and consumes UDP-α-D-galactofuranose as a sugar donor. Its optimal pH range is 6.5-7.5 and its optimal temperature range is 20-30°C. 1H-NMR, 13C-NMR and methylation analyses of fungal-type galactomannan extracted from the δAfgfsA strain revealed that AfGfsA is responsible for the biosynthesis of β1,5-galactofuranose in the galactofuran side chain of fungal-type galactomannan. Based on these results, we conclude that AfGfsA acts as a UDP-α-D-galactofuranose: β-D-galactofuranoside β1,5-galactofuranosyltransferase in the biosynthetic pathway of galactomannans.

Original languageEnglish
Pages (from-to)568-581
Number of pages14
JournalGlycobiology
Volume27
Issue number6
DOIs
Publication statusPublished - Jun 1 2017

Keywords

  • Aspergillus
  • Cell wall
  • Galactofuranose
  • Galactomannan
  • Glycosyltransferase

ASJC Scopus subject areas

  • Biochemistry

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    Katafuchi, Y., Li, Q., Tanaka, Y., Shinozuka, S., Kawamitsu, Y., Izumi, M., Ekino, K., Mizuki, K., Takegawa, K., Shibata, N., Goto, M., Nomura, Y., Ohta, K., & Oka, T. (2017). GfsA is a β1,5-galactofuranosyltransferase involved in the biosynthesis of the galactofuran side chain of fungal-type galactomannan in Aspergillus fumigatus. Glycobiology, 27(6), 568-581. https://doi.org/10.1093/glycob/cwx028