NopB, a Type III Secreted Protein of Rhizobium sp. Strain NGR234, Is Associated with Pilus-Like Surface Appendages

AUTOR(ES)

Saad, Maged M.

FONTE

American Society for Microbiology

RESUMO

Rhizobium sp. strain NGR234 possesses a functional type three secretion system (TTSS), through which a number of proteins, called nodulation outer proteins (Nops), are delivered to the outside of the cell. A major constraint to the identification of Nops is their low abundance in the supernatants of NGR234 strains grown in culture. To overcome this limitation, a more sensitive proteomics-based strategy was developed. Secreted proteins from wild-type NGR234 were separated by two-dimensional gel electrophoresis, and the gel was compared to similar gels containing the proteins from a TTSS mutant (NGRΩrhcN). To identify the proteins, spots unique to the NGR234 gels were analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry and the data were compared to the sequence of the symbiotic plasmid of NGR234. A nonpolar mutant of one of these proteins was generated called NopB. NopB is required for Nop secretion but inhibits the interaction with Pachyrhizus tuberosus and augments nodulation of Tephrosia vogelii. Flavonoids and a functional TTSS are required for the formation of some surface appendages on NGR234. In situ immunogold labeling and isolation of these pili showed that they contain NopB.

Documentos Relacionados

• Characterization of NopP, a Type III Secreted Effector of Rhizobium sp. Strain NGR234
• NopL, an Effector Protein of Rhizobium sp. NGR234, Thwarts Activation of Plant Defense Reactions1
• Rhizobium sp. strain NGR234 NodZ protein is a fucosyltransferase.
• An Evolutionary Hot Spot: the pNGR234b Replicon of Rhizobium sp. Strain NGR234
• Dynamics of Genome Architecture in Rhizobium sp. Strain NGR234†