Molecular characterization of a saline-soluble lectin from a parasitic fungus. Extensive sequence similarities between fungal lectins.
It has been proposed that the interactions between several parasitic and pathogenic fungi and their hosts are mediated by soluble lectins present in the fungus. We have cloned and analyzed a gene encoding such a lectin (AOL) from the nematophagous fungus Arthrobotrys oligospora (deuteromycete). The deduced primary structure of the AOL gene displayed an extensive similarity (identity 46.3%) to that of a gene encoding a lectin (ABL) recently isolated from the mushroom Agaricus bisporus (basidiomycete), but not to any other fungal, microbial, plant or animal lectins. The similarities between AOL and ABL were further demonstrated by the observation that an antibody specific for AOL cross-reacted with ABL. Together with data showing that AOL has a binding specificity that is similar to that of ABL [Rosen, S., Bergström, J., Karlsson, K.-A. & Tunlid, A. (1996) Eur. J. Biochem. 238, 830-837], these results indicate that AOL and ABL are members of a novel family of saline soluble lectins present in fungi. Southern blots indicated that there is only one AOL gene in the genome encoding a subunit (monomer) of the lectin. The primary structure of AOL did not show the presence of a typical N-terminal signal sequence. Comparison of the deduced primary structure with the molecular mass of AOL as determined by electrospray mass spectrometry (16153 Da), indicated that AOL has an acetylated N-terminal but no other post-translational modifications, and that a minor isoform is formed by deamidation. Circular dichroism (CD) spectroscopy suggested that the secondary structure of AOL contains 34% beta-sheets, 21% alpha-helix, and 45% turns and coils.
Rosén
S
S
Department of Microbial Ecology, Lund University, Sweden.
Kata
M
M
Persson
Y
Y
Lipniunas
P H
PH
Wikström
M
M
Van Den Hondel
M J
MJ
Van Den Brink
J
J
Rask
L
L
Hedén
L O
LO
Tunlid
A
A
D000364:Agaricus / Q000737:chemistry; D000595:Amino Acid Sequence; D000918:Antibody Specificity; D001483:Base Sequence; D015139:Blotting, Southern; D002240:Carbohydrate Sequence; D002942:Circular Dichroism; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology; D005800:Genes, Fungal; D006031:Glycosylation; D007527:Isoenzymes; D037102:Lectins / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology; D013058:Mass Spectrometry / Q000379:methods; D003904:Mitosporic Fungi / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride; D012995:Solubility
C100687:AOL protein, Arthrobotrys oligospora; D005656:Fungal Proteins; D007527:Isoenzymes; D037102:Lectins; D012965:Sodium Chloride