Regulation of Nitrogen Metabolism

Adds material on the regulation of nitrogen metabolism at the level of transcription... 

Marzluf, G.A. (1981). Regulation of nitrogen metabolism and gene expression in fungi. Microbiological Reviews 45, 437-61. 

Marzluf, G. A. (1996). Regulation of nitrogen metabolism in mycelial fungi. In The Mycota, Vol. III. Biochemistry and Molecular Biology, ed. R. Brambl G. A. Marzluf Berlin Springer-Verlag, pp. 357-68. 

While the expression and regulation of the urea cycle are widely appreciated (Campbell, 1991, 1995 Walsh and Mommsen, 2000), a few general functional properties of this pathway of nitrogen metabolism need to be mentioned here. 

For example, for deciding on the type of carbon source, the phenomenon of catabolite repression must be considered. Similarly, regulation of nitrogen and sometimes phosphorus metabolism are important factors to consider. Sometimes high concentrations of salts and free amino acids necessary for high cell density are inhibitory to product formation. One area often overlooked is the elimination of unwanted impurities, derived either from the raw material or produced via metabolism. These impurities represent not only a waste of the carbon source, but their accumulation at high levels may lead to inhibition of growth or even cell death. 

Of all bacterial GDH s, only the one from Thiobacillus novellus is strongly affected by a purine nucleotide, AMP, but in a fashion which is distinct from that in which animal enzymes are regulated (S3). Since few regulatory features have been established for bacterial enzymes, it is unlikely that GDH constitutes a major point of control of nitrogen metabolism in these organisms. 

Demain AL, Vaishnav P. (2003) Nitrogen regulation of biosynthesis of antibiotics and other secondary metabolic products. Pharma Chem 2(10) 92-96. 

The signal transduction pathways that mediate the effects of the metabolic hormone insulin are of particular medical interest (see A). The mediator nitrogen monoxide (NO) is also clinically important, as it regulates vascular caliber and thus the body s perfusion with blood (see B). 

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