The interaction of Vatairea macrocarca and Rhizobium tropici: net H+ efflux stimulus and alteration of extracellular Na+ concentration.
We studied the effect of a lectin isolated from seeds of the legume Vatairea macrocarpa on net H+ efflux in Rhizobium tropici, a bacterium capable of nodulating legume Phaseolus vulgaris. V. macrocarpa lectin (VML) was observed to temporarily stimulate the specific net H(+) efflux in R. tropici. When VML was present at 32 microg ml(-1), with or without 2 microM galactose (Gal), a specific net efflux >2.4 pM H+(min)(-1) mg dry biomass(-1) was induced. There was no detectable net H+ efflux when bovine serum albumin (16 microg ml(-1)) was tested. Addition of 16 microgVMLml(-1) resulted in a 700% increase of the extracellular Na+ concentration. The soluble proteins in the supernatant containing VML extract indicate a maximum immobilization of +/-10 microgVMLml(-1), with a minimum of 36,600 dimers or 8500 larger aggregates of VML binding in each bacterium. Our data suggest that VML activates Rhizobium as a bioenergetic substrate molecule, resulting in potential alterations of the external bacterial membrane.
Martínez
Cosme R
CR
Instituto Tecnológico do Estado de Pernambuco, Recife-Brasil. cosme@lika.ufpe.br
Chanway
Christopher P
CP
Albertini
Alessandro V P
AV
Figueiredo
Márcia V B
MV
Sampaio
Alexandre H
AH
Castellon
Rolando R
RR
Cavada
Benildo S
BS
Lima-Filho
José L
JL
D019281:Dimerization; D007887:Fabaceae / Q000737:chemistry*; D005690:Galactose / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D017136:Ion Transport / Q000187:drug effects; D037102:Lectins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D011485:Protein Binding; D042162:Rhizobium tropici / Q000187:drug effects* / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism
D037102:Lectins; D006859:Hydrogen; D012964:Sodium; D011188:Potassium; D005690:Galactose