Document Type
Article
Abstract
In many filamentous cyanobacteria nitrogen fixation occurs in differentiated cells called heterocysts. Filamentous strains that do not form heterocysts may fix nitrogen in vegetative cells, primarily under anaerobic conditions. We describe here two functional Mo-dependent nitrogenases in a single organism, the cyanobacterium Anabaena variabilis. Using a lacZ reporter with a fluorescent beta-galactoside substrate for in situ localization of gene expression, we have shown that the two clusters of nif genes are expressed independently. One nitrogenase functions only in heterocysts under either aerobic or anaerobic growth conditions, whereas the second nitrogenase functions only under anaerobic conditions in vegetative cells and heterocysts. Differences between the two nif clusters suggest that the nitrogenase that is expressed in heterocysts is developmentally regulated while the other is regulated by environmental factors.
Publication Date
September 1995
Publication Title
Proceedings of the National Academy of Sciences of the United States of America
Volume
92
Issue
20
First Page
9358
Last Page
9362
DOI
10.1073/pnas.92.20.9358
Recommended Citation
Thiel, T; Lyons, E; Erker, J; and Ernst, A, "A Second Nitrogenase in Vegetative Cells of a Heterocyst-Forming Cyanobacterium" (1995). Biology Department Faculty Works. 24.
DOI: https://doi.org/10.1073/pnas.92.20.9358
Available at:
https://irl.umsl.edu/biology-faculty/24