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JOURNAL OF BACTERIOLOGY, Nov. 1979, p. 597-606 Vol. 140, No. 2 0021-9193/79/11-0597/10$02.00/0
 

Summary: JOURNAL OF BACTERIOLOGY, Nov. 1979, p. 597-606 Vol. 140, No. 2
0021-9193/79/11-0597/10$02.00/0
Glutamine Synthetase Mutations Which Affect Expression of
Nitrogen Fixation Genes in Klebsiellapneumoniae
FREDERICK M. AUSUBEL,* STEPHANIE C. BIRD,t KAREN J. DURBIN,i KAAREN A.
JANSSEN,§ ROBERT F. MARGOLSKEE,II AND ADELE P. PESKIN§§
Department ofBiology, Cellular and Developmental Group, The Biological Laboratories, Harvard
University, Cambridge, Massachusetts 02138
Received for publication 16 August 1979
Previous studies have implicated glutamine synthetase (L-glutamate:ammonia
ligase [adenosine diphosphate forming], EC 6.3.1.2) as a major controlling element
of the nitrogen fixation (nif) genes in Klebsiellapneumoniae. We report here the
isolation of a new class of K. pneumoniae mutants which exhibit altered patterns
of nif and hut (histidine utilization) regulation. The expression of nif in these
mutants, which were isolated as Gln+ (glutamine nonrequiring) revertants of a
particular ginA mutation, is extremely sensitive to ammonia repression. These
mutants have a Nif- Hut- phenotype at external ammonia concentrations at
which wild-type strains are Nif+ Hut'. On the other hand, these mutants can be
fully derepressed for nif at very low ammonia concentrations. We adopted the
nomenclature "GlnR- (Nif- Hut-)" to facilitate discussion of the phenotype of

  

Source: Ausubel, Frederick M. - Department of Genetics, Harvard University

 

Collections: Biology and Medicine