Arrangement of nitrogenase structural genes in an aerobic filamentous nonheterocystous cyanobacterium.

Circadian Rhythm of Nitrogenase Gene Expression in the Diazotrophic Filamentous Nonheterocystous Cyanobacterium Trichodesmium sp. Strain IMS

Circadian rhythm of nitrogenase gene expression in the diazotrophic filamentous nonheterocystous cyanobacterium Trichodesmium sp. strain IMS 101.

Recent studies suggested that the daily cycle of nitrogen fixation activity in the marine filamentous nonheterocystous cyanobacterium Trichodesmium sp. is controlled by a circadian rhythm. In this study, we evaluated the rhythm of nitrogen fixation in Trichodesmium sp. strain IMS 101 by using the three criteria for an endogenous rhythm. Nitrogenase transcript abundance oscillated with a period ...

Transcriptional regulators ChlR and CnfR are essential for diazotrophic growth in nonheterocystous cyanobacteria.

Leptolyngbya boryana (Plectonema boryanum) is a diazotrophic cyanobacterium lacking heterocysts. How nitrogen fixation is regulated in filamentous nonheterocystous cyanobacteria remains unclear. Here we describe a large 50-kb nitrogen fixation (nif) gene cluster in L. boryana containing 50 genes. This gene cluster contains 14 nif genes (nifBSUHDKVZT and nifPENXW), two genes encoding transcripti...

A second nitrogenase in vegetative cells of a heterocyst-forming cyanobacterium.

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-gal...

Temporal Variability in Nitrogenase Gene Expression in Natural Populations of the Marine Cyanobacterium Trichodesmium thiebautii.

We report a distinct diel periodicity in the abundance of nifH (dinitrogenase reductase) mRNA in natural populations of the nonheterocystous marine cyanobacterium Trichodesmium thiebautii. Our observations show that in addition to translational and posttranslational controls, Trichodesmium nitrogenase expression is also regulated at the transcriptional and/or posttranscriptional level.