The products of Rhizobium genes, psi and pss, which affect exopolysaccharide production, are associated with the bacterial cell surface.
Translational fusions between a mutant phoA (lacking its promoter, ribosomal binding site and signal peptide sequence) and Rhizobium 'symbiotic' genes were isolated. Since these fusions expressed alkaline phosphatase (AP), the product of phoA, the genes into which phoA was inserted apparently specify proteins located in the bacterial periplasm or cell membrane, the compartment in which AP has activity. These genes were psiA and genes upstream of psiA (psiA is required for normal nodule development and strains with multicopy psiA fail to make exopolysaccharide (EPS) and to nodulate). Fusions between phoA and pss (exo) genes, which are required for EPS production, also resulted in the expression of AP indicating that products of these pss genes were located at the cell surface. Using gus fusions to psiA and pssA, we found that the former was expressed in N2-fixing bean root nodules but the latter was not.
Latchford
J W
JW
School of Ocean Sciences, University College of North Wales, Gwynedd, UK.
Borthakur
D
D
Johnston
A W
AW
D000469:Alkaline Phosphatase / Q000235:genetics; D001693:Biological Transport, Active / Q000235:genetics; D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D007887:Fabaceae / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D010946:Plants, Medicinal; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D011993:Recombinant Fusion Proteins; D012231:Rhizobium / Q000235:genetics* / Q000472:pathogenicity; D013559:Symbiosis / Q000235:genetics
D004251:DNA Transposable Elements; D008565:Membrane Proteins; D011135:Polysaccharides, Bacterial; D011993:Recombinant Fusion Proteins; D000469:Alkaline Phosphatase