Characterization of the Sinorhizobium meliloti genes encoding a functionaldihydrodipicolinate synthase (dapA) and dihydrodipicolinate reductase (dapB)

Citation
Fm. Garcia-rodriguez et al., Characterization of the Sinorhizobium meliloti genes encoding a functionaldihydrodipicolinate synthase (dapA) and dihydrodipicolinate reductase (dapB), ARCH MICROB, 173(5-6), 2000, pp. 438-444
Citations number
29
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
ARCHIVES OF MICROBIOLOGY
ISSN journal
0302-8933 → ACNP
Volume
173
Issue
5-6
Year of publication
2000
Pages
438 - 444
Database
ISI
SICI code
0302-8933(200005/06)173:5-6<438:COTSMG>2.0.ZU;2-Y
Abstract
In bacteria, the known pathways for diaminopimelate (DAP) and lysine biosyn thesis share two key enzymes, dihydrodipicolinate synthase and dihydrodipic olinate reductase, encoded by the dapA and dapB genes, respectively. In rhi zobia, these genes have not yet been genetically characterized. In this wor k, by sequence analysis, we identified two divergent open reading frames on the 140-MDa plasmid pRmeGR4b of Sinorhizobium meliloti strain GR4. Termed dapA and dapB, these encode products which show significant sequence simila rities to DapA and DapB proteins, respectively. Escherichia coli DAP auxotr ophs (dapA and dapB mutants) could be complemented with the pRmeGR4b dapA a nd dapB genes, indicating that these genes code for functional dihydrodipic olinate synthase and dihydrodipicolinate reductase, respectively. Reverse-t ranscriptase PCR analyses and P-galactosidase assays using transcriptional dapA-lacZ and dapB-lacZ fusions suggest that these genes are constitutively expressed in S. meliloti. The dapA and dapB genes are not widely distribut ed in S. meliloti and appear to be specific for strains carrying pRmeGR4b-t ype plasmids.