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Science 4 April 1986:
Vol. 232. no. 4746, pp. 92 - 94
DOI: 10.1126/science.232.4746.92
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Articles

Nitrogen Fixation by Azotobacter vinelandii Strains Having Deletions in Structural Genes for Nitrogenase

PAUL E. BISHOP 1, R. PREMAKUMAR 1, DENNIS R. DEAN 2, MARTY R. JACOBSON 1, JOHN R. CHISNELL 1, THOMAS M. RIZZO 1, and JENNIFER KOPCZYNSKI 1

1 U.S. Department of Agriculture, Agricultural Research Service, and Department of Microbiology, North Carolina State University, Raleigh, NC 27695.
2 Department of Anaerobic Microbiology Virginia Polytechnic Institute, Blacksburg, VA 24061.

Phenotypic reversal of Nif- mutant strains to Nif+ under molybdenum-deficient conditions has been cited as evidence that Azotobacter vinelandii possesses two nitrogen fixation systems: the conventional molybdenum-enzyme system and an alternative nitrogen-fixation system. Since explanations other than the existence of an alternative system were possible, deletion strains of A. vinelandii lacking the structural genes for conventional nitrogenase (nifHDK) were constructed. These strains were found to grow in molybdenum-deficient nitrogen-free media, reduce acetylene (at low rates), and incorporate molecular nitrogen labeled with nitrogen-15. Thus it can be concluded that the phenotypic reversal phenomenon cannot be due to altered phenotypic expression of nif mutations under molybdenum-deficient conditions, but is due to the existence of an alternative nitrogen-fixation system in A. vinelandii as originally proposed.

Submitted on September 20, 1985
Accepted on December 16, 1985


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Maturation of Nitrogenase: a Biochemical Puzzle.
L. M. Rubio and P. W. Ludden (2005)
J. Bacteriol. 187, 405-414
   Full Text »    PDF »
VnfY Is Required for Full Activity of the Vanadium-Containing Dinitrogenase in Azotobacter vinelandii.
C. Ruttimann-Johnson, L. M. Rubio, D. R. Dean, and P. W. Ludden (2003)
J. Bacteriol. 185, 2383-2386
   Abstract »    Full Text »    PDF »
Incorporation of Molybdenum into the Iron-Molybdenum Cofactor of Nitrogenase.
R. M. Allen, J. T. Roll, P. Rangaraj, V. K. Shah, G. P. Roberts, and P. W. Ludden (1999)
J. Biol. Chem. 274, 15869-15874
   Abstract »    Full Text »    PDF »
Characteristics of NIFNE in Azotobacter vinelandii Strains.
J. T. Roll, V. K. Shah, D. R. Dean, and G. P. Roberts (1995)
J. Biol. Chem. 270, 4432-4437
   Abstract »    Full Text »    PDF »
The chaperone GroEL is required for the final assembly of the molybdenum-iron protein of nitrogenase.
M. W. Ribbe and B. K. Burgess (2001)
PNAS 98, 5521-5525
   Abstract »    Full Text »    PDF »


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