Lectins associated with the bacterial cell surface of Rhizobium lupini
strain LL13 were evidenced by erythrocyte agglutination, by aggregati
on of neoglycoprotein coated beads and by spectrofluorimetry using flu
oresceinylated neoglycoproteins. At pH 5.0, a specific binding of the
fluorescein-labelled neoglycoprotein bearing alpha-L-fucose was observ
ed. The binding of this labelled neoglycoprotein is a saturable phenom
enon and is inhibited by the same unlabelled neoglycoprotein. Extracts
of R lupini obtained by disrupting a bacterial pellet through a Frenc
h press were stabilized at pH 5.6 by gel filtration and purified to ho
mogeneity by affinity chromatography on Agarose A4 substituted with al
pha-L-fucose. A protein with a M(r) approximate to 19 000 was specific
ally eluted from this affinity column with L-fucose. Isoelectric focus
ing of this sample yielded a single band with pi near 6.7. This protei
n specifically aggregated L-Fuc-BSA-coated microspheres. The results o
btained in the present study indicate that we have purified from Rhizo
bium lupini strain LL13, a L-fucose binding protein as a lectin.