The nodulation-signaling protein NodO from Rhizobium leguminosarum biovar viciae forms ion channels in membranes.
AUTOR(ES)
Sutton, J M
RESUMO
The secreted nodulation-signaling protein NodO was purified from the supernatant of cultures of Rhizobium leguminosarum biovar viciae. The native protein has a M(r) of approximately 67,000, suggesting that it exists as a dimer since the DNA sequence predicts a M(r) of 30,002. Pure NodO protein had no protease, pectinase, or cellulase activity, and no binding was observed to lipooligosaccharide nodulation factors. Although NodO is relatively hydrophilic, it appeared to insert into liposomes and was protected by liposomes from proteolytic cleavage. When added to planar lipid bilayers, NodO formed cation-selective channels that allowed the movement of monovalent cations (K+ and Na+) across the membrane. NodO is a Ca(2+)-binding protein; in the presence of high concentrations of Ca2+, channel activity was reduced. We hypothesize that NodO plays a role in nodulation signaling by stimulating uptake of nodulation factors or by forming cation-specific channels that function synergistically with the proposed lipooligosaccharide-induced depolarization of the plasma membrane of leguminous plants.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=44943Documentos Relacionados
- nodO, a new nod gene of the Rhizobium leguminosarum biovar viciae sym plasmid pRL1JI, encodes a secreted protein.
- The NodD protein does not bind to the promoters of inducible nodulation genes in extracts of bacteroids of Rhizobium leguminosarum biovar viciae.
- Suppression of nodulation gene expression in bacteroids of Rhizobium leguminosarum biovar viciae.
- Identification and Characterization of Nodulation-Signaling Pathway 2, a Gene of Medicago truncatula Involved in Nod Factor Signaling1
- Rhizobium leguminosarum Biovar viciae 1-Aminocyclopropane-1-Carboxylate Deaminase Promotes Nodulation of Pea Plants