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Pleiotropic effect of his gene mutations on nitrogen fixation in Klebsiella pneumoniae
Author(s) -
Jensen Jens Stougaard,
Kennedy Christina
Publication year - 1982
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1982.tb01147.x
Subject(s) - nitrogen fixation , fixation (population genetics) , klebsiella pneumoniae , mutant , nitrogenase , gene , biology , genetics , bacteria , escherichia coli
Several his mutations were found to influence nitrogen fixation in Klebsiella pneumoniae: hisB, hisC , and hisD mutants had 50% of wild‐type levels of nitrogenase activity when supplied with 30 μg or less histidine/ml although this concentration did not limit protein synthesis and the mutants retained a Nif + plate phenotype. A hisA mutation had a similar but more dramatic effect. At low concentrations of histidine the hisA mutant strain had only 5% of the nitrogenase activity found at high histidine concentration or in a his + strain, and was also Nif ‐ on low histidine agar plates. Addition of adenine restored nitrogenase activity in the hisA but not the hisB, hisC , or hisD mutants. Low levels of intracellular ATP, a consequence of hisG enzyme activity, correlated with loss of nitrogen‐fixing ability in the hisA mutant which failed to sustain nif gene expression under these conditions. Synthesis of other major cell proteins was relatively unaffected indicating that nif gene expression is selectively regulated by the energy status of the organism.