FRUITING BODY-SPECIFIC CDNA, MFBAC, FROM THE MUSHROOM LENTINUS-EDODESENCODES A HIGH-MOLECULAR-WEIGHT CELL-ADHESION PROTEIN CONTAINING AN ARG-GLY-ASP MOTIF

A cDNA clone (designated mfbAc), encoding 2157 amino acids (aa), was i solated from a mature fruiting-body cDNA library of the edible mushroo m Lentinus edodes, The mfbA transcript was abundant in mature fruiting bodies, detectable in immature fruiting bodies but absent in earlier developmental stages and in the vegetative mycelium. Although more abu ndant in the pileus than the stipe, only low levels were found in the gill tissue. The deduced MFBA protein (234.5 kDa) contained a cell-sur face attachment-promoting Arg-Gly-Asp (RGD) motif. MFBA was produced i n Escherichia coli using a maltose-binding protein (MBP) fusion vector , but it was cleaved into four fragments even in a protease-deficient host. A 425-aa MFBA peptide containing the RGD motif (named MFBA(582-1 006) peptide) was successfully produced using the phage T7 expression system. This MFBA(582-1006) peptide exhibited a cell adhesion and spre ading activity toward mammalian cells. This activity of the MFBA fragm ent was competitively inhibited by the Gly-Arg-Gly-Asp-Ser-Pro peptide but not by the Gly-Arg-Gly-Glu-Ser-Pro peptide, showing that the RGD motif of MFBA is essential for the cell-binding activity.