A (1-->3)-beta-D-glucan recognition protein from the sponge Suberites domuncula. Mediated activation of fibrinogen-like protein and epidermal growth factor gene expression.
Sponges (phylum Porifera) live in a symbiotic relationship with microorganisms, primarily bacteria. Until now, molecular proof for the capacity of sponges to recognize fungi in the surrounding aqueous milieu has not been available. Here we demonstrate, for the demosponge Suberites domuncula (Porifera, Demospongiae, Hadromerida), a cell surface receptor that recognizes (1-->3)-beta-D-glucans, e.g. curdlan or laminarin. This receptor, the (1-->3)-beta-D-glucan-binding protein, was identified and its cDNA analysed. The gene coding for the 45 kDa protein was found to be upregulated in tissue after incubation with carbohydrate. Simultaneously with the increased expression of this gene, two further genes showed an elevated steady state level of expression; one codes for a fibrinogen-like protein and the other for the epidermal growth factor precursor. Expression of the (1-->3)-beta-D-glucan-binding protein and the fibrinogen-like protein occurred in cells on the sponge surface, in the pinacoderm. By Western blotting, the product of the fibrinogen-like protein gene was identified, the recombinant protein isolated, and antibodies raised to this protein. Their application revealed that a 5 kDa factor is produced, which is apparently processed from the 77 kDa epidermal growth factor precursor. Finally, we provided evidence that a tyrosine kinase pathway is initiated in response to exposure to D-glucan; its phosphorylation activity could be blocked by aeroplysinin. In turn, the increased expression of the downstream genes was suppressed. We conclude that sponges possess a molecular mechanism for recognizing fungi via the d-glucan carbohydrates on their surfaces.
Perović-Ottstadt
Sanja
S
Institut für Physiologische Chemie, Abteilung Angewandte Molekularbiologie, Universität, Mainz, Germany.
Adell
Teresa
T
Proksch
Peter
P
Wiens
Matthias
M
Korzhev
Michael
M
Gamulin
Vera
V
Müller
Isabel M
IM
Müller
Werner E G
WE
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000096:biosynthesis / Q000235:genetics; D005340:Fibrinogen / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D005936:Glucans / Q000378:metabolism* / Q000494:pharmacology; D037102:Lectins; D008969:Molecular Sequence Data; D010766:Phosphorylation; D010802:Phylogeny; D011161:Porifera / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D047071:beta-Glucans
D002352:Carrier Proteins; D005936:Glucans; D037102:Lectins; D011498:Protein Precursors; D011994:Recombinant Proteins; D047071:beta-Glucans; C042652:epidermal growth factor precursor; C037937:glucan-binding proteins; D004815:Epidermal Growth Factor; C038459:curdlan; D005340:Fibrinogen; C033363:beta-1,3-glucan