The interaction of Vatairea macrocarca and Rhizobium tropici: net H+ efflux stimulus and alteration of extracellular Na+ concentration |
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Authors: | Martínez Cosme R Chanway Christopher P Albertini Alessandro V P Figueiredo Márcia V B Sampaio Alexandre H Castellon Rolando R Cavada Benildo S Lima-Filho José L |
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Affiliation: | Instituto Tecnológico do Estado de Pernambuco, Recife-Brasil. cosme@lika.ufpe.br |
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Abstract: | 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. |
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Keywords: | Ion transport Rhizobium Lectin Vatairea macrocarpa |
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