Molecular analysis of the Rhizobium meliloti mucR gene regulating the biosynthesis of the exopolysaccharides succinoglycan and galactoglucan
| Autor: | Alfred Pühler, Doris Jording, Jürgen Quandt, Walter Arnold, Wm Weng, A Roxlau, M. Keller, Karsten Niehaus, Michael Schmidt |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
DNA
Bacterial EXOPOLYSACCHARIDE SYNTHESIS Transcription Genetic Physiology Mutant Molecular Sequence Data Marker gene Galactans GENE REGULATION Bacterial Proteins Gene expression Amino Acid Sequence Gene Glucans Genetics biology Base Sequence Sequence Homology Amino Acid SYMBIOSIS Polysaccharides Bacterial Nucleic acid sequence food and beverages General Medicine Agrobacterium tumefaciens Gene Expression Regulation Bacterial biology.organism_classification Repressor Proteins Open reading frame Biochemistry Carbohydrate Sequence Mutation Rhizobium Agronomy and Crop Science Sinorhizobium meliloti Transcription Factors |
| Zdroj: | Molecular plant-microbe interactions : MPMI. 8(2) |
| ISSN: | 0894-0282 3055-3059 |
| Popis: | The Rhizobium meliloti Tn5 mutant Rm3131, producing galactoglucan (EPS II) instead of succinoglycan (EPS I), was complemented by a 3.6-kb EcoRI-fragment of the Rhizobium meliloti genome. Sequencing of this fragment revealed six open reading frames (ORFs). The ORF found to be affected in the mutant Rm3131 codes for a putative protein of 15.7 kDa and forms a monocistronic transcriptional unit. Further genetic analysis revealed that the gene mutated in Rm3131 is identical to the previously described R. meliloti mucR gene (H. Zhan, S. B. Levery, C. C. Lee, and J. A. Leigh, 1989, Proc. Natl. Acad. Sci. USA 86:3055-3059). By hybridization it was shown that a mucR homologous gene is present in several rhizobacteria. The deduced amino acid sequence of MucR showed nearly 80% identity to the Agrobacterium tumefaciens Ros protein, a negative regulator of vir genes and necessary for succinoglycan production. MucR contains like Ros a putative zinc finger sequence of the C2H2 type. Transcriptional fusions of genes for EPS I and EPS II synthesis, the so-called exo and exp genes, with the marker gene lacZ were used to delineate the role of mucR for exo and exp gene expression. It was found that exp genes are negatively regulated by MucR on the transcriptional level, whereas a posttranscriptional regulation by MucR is assumed for exo genes. Furthermore, mucR is negatively regulating its own transcription. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|