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Lookup NU author(s): Dr Fernando Santos Beneit
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The metabolism of soil-dwelling actinobacteria is very complex because they have to cope with a variety of nutrients in soil and sometimes with drastic changes in the environmental conditions. For these reasons some actinobacteria, particularly species of the genus Streptomyces and related so-called “rare actinomycetes”, are equipped with large genomes (7 to 11 Mb) that encode many biosynthetic pathways for the production of secondary metabolites and multiple regulatory proteins. Among these proteins are particularly relevant the global regulators because they control many metabolic processes. These global regulators respond to a variety of nutritional and environmental stress signals. However, these global regulators do not act independently of each other; in the last decade an increasing number of cross-talks have been reported and they reveal sophisticated “compensatory” mechanisms to keep a metabolic equilibrium (homeostasis) that prevents irreversible cell damage due to the lack (or toxic excess) of essential metabolic intermediates. Particularly relevant is the cross-talk of the global regulators PhoP and GlnR that control phosphate and nitrogen metabolism, respectively. Expression of glnR and several other genes involved in nitrogen metabolism is under the control of PhoP. These two global regulators cross-talk with AfsR, a pleiotropic regulator that controls antibiotic biosynthesis in several Streptomyces species. These global regulators also interact with other regulators, such as the AfsQ1 response regulator and the DasR wide-domain regulator, that controls chitin degradation and N–acetylglucosamine metabolism. In addition, DasR binds to the promoter of the gene encoding the general iron regulator DmdR1,that controls siderophore biosynthesis and iron metabolism. Iron capture and transport are key processes for actinobacteria survival in soil. Some other regulators, like ArgR, that was previously thought to be specific for the control of one (or a few) biosynthetic pathway(s), is now known to control many other regulatory genes, sigma factors and two-component systems, forming an intrincate regulatory web. We propose that cross-talk of global regulators acts as a “protection net” to avoid lethal metabolic imbalances by regulating the cell metabolism.
Author(s): Martín JF, Santos-Beneit F, Sola-Landa A, Liras P
Editor(s): de Bruijn,FJ
Publication type: Book Chapter
Publication status: Published
Book Title: Stress and Environmental Regulation of Gene Expression and Adaptation in Bacteria
Year: 2016
Pages: 257-262
Print publication date: 19/08/2016
Acceptance date: 02/11/2015
Number of Volumes: 2
Publisher: Wiley-Blackwell
Place Published: New York
URL: http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1119004888.html
Library holdings: Search Newcastle University Library for this item
ISBN: 9781119004882
