Mycobiology.  2014 Jun;42(2):167-173.

Cloning and Molecular Characterization of beta-1,3-Glucan Synthase from Sparassis crispa

Affiliations
  • 1Division of Applied Life Science (BK21Plus) and Research Institute of Life Sciences, Gyeongsang National University, Jinju 660-701, Korea. rohyeon@gnu.ac.kr

Abstract

A beta-glucan synthase gene was isolated from the genomic DNA of polypore mushroom Sparassis crispa, which reportedly produces unusually high amount of soluble beta-1,3-glucan (beta-glucan). Sequencing and subsequent open reading frame analysis of the isolated gene revealed that the gene (5,502 bp) consisted of 10 exons separated by nine introns. The predicted mRNA encoded a beta-glucan synthase protein, consisting of 1,576 amino acid residues. Comparison of the predicted protein sequence with multiple fungal beta-glucan synthases estimated that the isolated gene contained a complete N-terminus but was lacking approximately 70 amino acid residues in the C-terminus. Fungal beta-glucan synthases are integral membrane proteins, containing the two catalytic and two transmembrane domains. The lacking C-terminal part of S. crispa beta-glucan synthase was estimated to include catalytically insignificant transmembrane alpha-helices and loops. Sequence analysis of 101 fungal beta-glucan synthases, obtained from public databases, revealed that the beta-glucan synthases with various fungal origins were categorized into corresponding fungal groups in the classification system. Interestingly, mushrooms belonging to the class Agaricomycetes were found to contain two distinct types (Type I and II) of beta-glucan synthases with the type-specific sequence signatures in the loop regions. S. crispa beta-glucan synthase in this study belonged to Type II family, meaning Type I beta-glucan synthase is expected to be discovered in S. crispa. The high productivity of soluble beta-glucan was not explained but detailed biochemical studies on the catalytic loop domain in the S. crispa beta-glucan synthase will provide better explanations.

Keyword

beta-Glucan; Cell wall; Glucan synthase; Sparassis crispa

MeSH Terms

Agaricales
Cell Wall
Classification
Clone Cells*
Cloning, Organism*
DNA
Efficiency
Exons
Glycogen Synthase
Humans
Introns
Membrane Proteins
Open Reading Frames
RNA, Messenger
Sequence Analysis
DNA
Glycogen Synthase
Membrane Proteins
RNA, Messenger
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