IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
RapA2 is a calcium binding lectin that specifically recognizes Rhizobium leguminosarum acidic exopolysaccharides
Autor/es:
ABDIAN, P. L.; CARAMELO, J. J.; AUSMEES, N.; ZORREGUIETA, A.
Lugar:
Mar del Plata
Reunión:
Congreso; VIII Congreso Argentino de Microbiología General-SAMIGE; 2012
Institución organizadora:
UNMDP, FIBA, INTEMA, Fac. de Ingeniería
Resumen:
RapA are extracellular proteins secreted by the type I
PrsDE system of the closely related Rhizobium
leguminosarum biovars and Rhizobium
etli. At least three isoforms have been found in R. leguminosarum bv. trifolii
R200. The RapA1 isoform was first described as an agglutinin that localizes at
one cell pole. The exact role of RapA proteins
has not been determined yet. Structural similarity with eukaryotic cadherins
suggested that RapA proteins could be involved
in cellular aggregation by protein-protein interactions. A detailed biophysical
characterization showed that RapA2 does not mediate cellular interactions
through a cadherin-like mechanism. We have proposed that RapA
might be involved in the modulation of the acidic exopolysaccharide (EPS)
matrix structure during biofilm formation in static or continuous flow
conditions. Here we report a biochemical characterization of RapA2, the only isoform
present in R. leguminosarum bv. viciae 3841. Supporting previous
evidence, we showed that RapA2 interacts specifically with the acidic exopolysaccharides
produced by R. leguminosarum, and
that binding activity is completely dependent on the presence of calcium ions.
Inhibition binding assays indicate that glucuronic acid residues may be
implicated in the structure recognized by RapA2 on EPS and CPS (capsular
polysaccharide), both of which have similar structures. The results presented
here suggest that RapA proteins are
calcium-binding lectins and sustain a role of these proteins in the development
of the biofilm matrix made of EPS.