Isolation and characterization of Rhizobium tropici Nod factor sulfation genes.

TitleIsolation and characterization of Rhizobium tropici Nod factor sulfation genes.
Publication TypeJournal Article
Year of Publication1996
AuthorsLaeremans, T., I. Caluwaerts, C. Verreth, M. A. Rogel, J. Vanderleyden, and E. Martínez-Romero
JournalMol Plant Microbe Interact
Volume9
Issue6
Pagination492-500
Date Published1996 Aug
ISSN0894-0282
KeywordsAmino Acid Sequence, Bacterial Proteins, Base Sequence, Cloning, Molecular, DNA Primers, Fabaceae, Genes, Bacterial, Genetic Complementation Test, Molecular Sequence Data, Mutagenesis, Site-Directed, Nitrogen Fixation, Phenotype, Plants, Medicinal, Rhizobium
Abstract

Rhizobium tropici produces a mixture of sulfated and non-sulfated Nod factors. The genes responsible for the sulfation process in R. tropici strain CFN299 were cloned and sequenced. These genes are homologous to the nodP, nodQ, and nodH genes from R. meliloti. The identity among the two species is 75% for nodP, 74% for nodQ, and 69% for nodH. NodH resembles sulfotransferases in general and NodQ has the characteristic purine-binding motifs and the PAPS 3'-phosphoadenosine 5'-phosphosulfate) motif. Mutants of NodP and NodH were obtained by site-directed mutagenesis. They are no longer able to synthesize the sulfated Nod factor, as was demonstrated in high-pressure liquid chromatography and thin-layer chromatography assays. The NodP- mutant had a decreased nodulation capacity in Phaseolus vulgaris Negro Xamapa bean plants. In contrast, NodH- and NodP- mutants acquired an increased capacity to nodulate the high-nitrogen-fixing bean cultivars N-8-116 and BAT-477. Nodulation was restored to normal levels when the mutants were complemented with a 16-kb clone carrying the wild-type genes. The role of the sulfate on Nod factors in R. tropici was dependent on the bean cultivar and the conditions assayed.

Alternate JournalMol. Plant Microbe Interact.
PubMed ID8755625