E.coli aerobic/anaerobic switch studyChao Wang, Mar 1 2006
E.coli aerobic/anaerobic switch study Chao Wang, Mar 1 2006
The bacterium E. coli possesses a large number ofsensing/regulation systems for rapid response to environmentalchanges.Those regulation systems allow variation in the way electrons arechanneled from donor to terminal acceptors such that the overallpotential difference is maximized for any given growth conditionThe adaptive responses are coordinated by a group of globalregulators, which includes the one component furmarate & nitratereduction (FNR) protein, and the two-component anoxic redoxcontrol (Ar) systemWith the initial onset of anaerobiosis ArcA is activated, and ifthese conditions persist or become more anaerobic, FNR isactivated leading in turn to the upregulation of ArcA andamplification of its effect
The bacterium E. coli possesses a large number of sensing/regulation systems for rapid response to environmental changes. Those regulation systems allow variation in the way electrons are channeled from donor to terminal acceptors such that the overall potential difference is maximized for any given growth condition. The adaptive responses are coordinated by a group of global regulators, which includes the one component furmarate & nitrate reduction (FNR) protein, and the two-component anoxic redox control (Arc) system. With the initial onset of anaerobiosis ArcA is activated, and if these conditions persist or become more anaerobic, FNR is activated leading in turn to the upregulation of ArcA and amplification of its effect
Fnr ModulonFnr is a global transcription regulator with similarity to CRP; ithas 4 Cys residues that have been shown to bind a 4Fe-4Scluster under some conditions and 2 [2Fe-2S] centers underother conditions. Hence, a redox-sensitive confirmationalchange can occur that mediates control of transcription of ~30transcription units and >70 genes.For nitrate reductase, Fnr only potentiates expression. Nitratemust be present to relieve repression by NarX/NarL twocomponent sensor-regulator system
Fnr Modulon Fnr is a global transcription regulator with similarity to CRP; it has 4 Cys residues that have been shown to bind a 4Fe-4S cluster under some conditions and 2 [2Fe-2S] centers under other conditions. Hence, a redox-sensitive confirmational change can occur that mediates control of transcription of ~30 transcription units and >70 genes. For nitrate reductase, Fnr only potentiates expression. Nitrate must be present to relieve repression by NarX/NarL two component sensor-regulator system
ArcA/B ModulonIn this system, ArcB is the sensor kinase, and is a membranebound protein found in the cytoplasmic membrane. ArcA is theresponse regulator of the system and is a DNA-bindingtranscriptional regulator.The signal that causes autophosphorylation of ArcB andphosphotransfer to ArcA is not known, but is presumed to beeither the proton motive force or a redox signal, possibly theredox state of the quinone pool.Target genes include those encoding quinol oxidase, succinatedehydrogenase, superoxide dismutase and many others involvedin aerobic metabolism and energy production
ArcA/B Modulon In this system, ArcB is the sensor kinase, and is a membranebound protein found in the cytoplasmic membrane. ArcA is the response regulator of the system and is a DNA-binding transcriptional regulator. The signal that causes autophosphorylation of ArcB and phosphotransfer to ArcA is not known, but is presumed to be either the proton motive force or a redox signal, possibly the redox state of the quinone pool. Target genes include those encoding quinol oxidase, succinate dehydrogenase, superoxide dismutase and many others involved in aerobic metabolism and energy production
Metabolic networkThis system of connectedchemical reactionsisametabolicnetwork.TherawmetabolicdatacollectedatKEGG consistof a detailedlist ofbiochemicalreactions. Besides annotations for genes and genomes, KEGG containscomprehensive information on biochemical reactions,enzymes, andpathways.Transcriptional Regulation NetworkTranscriptional regulation is the mechanism that coordinatesthe expression ofgenetic information coded on the DNA with the needs of various lifeprocesses. The regulation of transcription factors and non-TF transcriptionunits form a network of transcriptional regulationGeneExpressionDataThe genome-scale cDNA microarray experiment measures the expressiondifferences under different conditionsfor virtuallyall genes of an organism
Metabolic network This system of connected chemical reactions is a metabolic network. The raw metabolic data collected at KEGG consist of a detailed list of biochemical reactions. Besides annotations for genes and genomes, KEGG contains comprehensive information on biochemical reactions, enzymes, and pathways. Transcriptional Regulation Network Transcriptional regulation is the mechanism that coordinates the expression of genetic information coded on the DNA with the needs of various life processes. The regulation of transcription factors and non-TF transcription units form a network of transcriptional regulation. Gene Expression Data The genome-scale cDNA microarray experiment measures the expression differences under different conditions for virtually all genes of an organism