Linked Life Data

588592

Source:http://linkedlifedata.com/resource/pubmed/id/588592

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1978-2-18
pubmed:abstractText
This communication describes the isolation and characterization of mutants of Rhizobium trifolii which can induce nitrogenase activity in defined liquid medium. Two procedures were used for the isolation of these mutants from R. trifolii strain DT-6: (1) following chemical mutagenesis, slow growing mutants were selected which were unable to utilize NH+4 as sole source of nitrogen; (2) as spontaneous mutants resistant to the glutamate analogue L-methionine-DL-sulfoximine. Mutants (DT-71, DT-125) isolated by these procedures induced nitrogenase activity in the free-living state, whereas the parent strain lacked this property. Induction of nitrogenase activity in these mutants occurred during the late exponential phase of growth when the rate of protein synthesis was decreasing. The addition of NH+4 to a medium containing glutamate as the nitrogen-source resulted in a 50--70% reduction (repression?) of nitrogenase activity; in contrast, the rate of protein synthesis or the rate of respiration was not influenced by exogenous NH+4. Biochemical analysis showed that these mutants (strains DT-71 and DT-125) have defects in both nitrogen and carbon metabolism. The levels of glutamate synthase (both NADP+ -and NAD+ -dependent activities) and glutamate dehydrogenase (NAD+-dependent activity) were markedly lower. In addition, the mutants were found to have no detectable ribitol dehydrogenase or beta-galactosidase activity. These findings are discussed in relation to a mechanism of regulation of symbiotic nitrogen fixation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
22
pubmed:volume
500
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
277-90
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1977
pubmed:articleTitle
Regulation of nitrogen fixation in Rhizobium spp. Isolation of mutants of Rhizobium trifolii which induce nitrogenase activity.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.