Nitrogen is a quantitatively important bioelement which is incorporated into the biosphere
through assimilatory processes carried out by microorganisms and plants. Numerous …

Nitrogen metabolism in prokaryotes involves the coordinated expression of a large number
of enzymes concerned with both utilization of extracellular nitrogen sources and intracellular …

Heterocysts are differentiated cells that are specialized for fixation of N 2 in an aerobic
environment. In heterocysts in the light, Photosystem I generates ATP, but no photosynthetic …

Many, though not all, non-heterocystous cyanobacteria can fix N2. However, very few strains
can fix N2 aerobically. Nevertheless, these organisms may make a substantial contribution …

Abstract The Crp-Fnr regulators, named after the first two identified members, are DNA-
binding proteins which predominantly function as positive transcription factors, though roles …

In cyanobacteria, after transport by specific permeases, ammonium is incorporated into
carbon skeletons by the sequential action of glutamine synthetase (GS) and glutamate …

Nitrate is a significant nitrogen source for plants and microorganisms. Recent molecular
genetic analyses of representative bacterial species have revealed structural and regulatory …

The element nitrogen (N) constitutes about 5-10% of the dry weight of a cyanobacterial cell.
The purpose of this chapter is to review the assimilatory pathways which in free-living …

In cyanobacteria, ammonium exerts a negative regulation of the expression of proteins
involved in the assimilation of nitrogen sources alternative to ammonium. In Synechococcus …

Cyanobacteria are one of the earliest branching groups of organisms on the planet, and
during their evolutionary history were submitted to varying selective pressures. Nowadays …