Expression of malT, the regulator gene of the maltose region in Escherichia coli, is limited both at transcription and translation.

Chapon, C

doi:10.1002/j.1460-2075.1982.tb01176.x

Cited by 73 publications

(68 citation statements)

References 25 publications

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“…Translational noise control is a means by which genetic circuits can reduce noise in such cascades. Regulatory genes such as the cI gene of phage (2) and the malT gene of Escherichia coli (19) are often poorly translated. It has been pointed out by other researchers (e.g., ref.…”

Section: Discussionmentioning

confidence: 99%

“…It has been pointed out by other researchers (e.g., ref. 19) that this translational inefficiency might be sustained in the genome through the resulting beneficial reduction in noise. However, we note that in some situations, the intrinsic noise of a regulator can actually increase the sensitivity with which its signal is transmitted (20,21).…”

Section: Discussionmentioning

confidence: 99%

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Intrinsic noise in gene regulatory networks

Thattai

Oudenaarden

2001

Proc. Natl. Acad. Sci. U.S.A.

1,345

1,441

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Cells are intrinsically noisy biochemical reactors: low reactant numbers can lead to significant statistical fluctuations in molecule numbers and reaction rates. Here we use an analytic model to investigate the emergent noise properties of genetic systems. We find for a single gene that noise is essentially determined at the translational level, and that the mean and variance of protein concentration can be independently controlled. The noise strength immediately following single gene induction is almost twice the final steady-state value. We find that fluctuations in the concentrations of a regulatory protein can propagate through a genetic cascade; translational noise control could explain the inefficient translation rates observed for genes encoding such regulatory proteins. For an autoregulatory protein, we demonstrate that negative feedback efficiently decreases system noise. The model can be used to predict the noise characteristics of networks of arbitrary connectivity. The general procedure is further illustrated for an autocatalytic protein and a bistable genetic switch. The analysis of intrinsic noise reveals biological roles of gene network structures and can lead to a deeper understanding of their evolutionary origin.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Intrinsic noise in gene regulatory networks

Thattai

Oudenaarden

2001

Proc. Natl. Acad. Sci. U.S.A.

1,345

1,441

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“…The maltose system is subjected to catabolite repression as well as inducer exclusion. Thus, the expression of malT as well as some of the MalT-dependent genes (i.e., the ones encoding transport proteins) is controlled by the cyclic AMP/catabolite gene activator protein system (10), which in turn is controlled by the PtsG-mediated transport of glucose (46). EIIA Glc -mediated catabolite repression on malT is also exerted by growth on glycerol, most likely affecting the EIIA Glc -P-dependent stimulation of adenylate cyclase by glycerol-3-P (19,20).…”

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confidence: 99%

The Maltodextrin System ofEscherichia coli: Metabolism and Transport

2005

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The maltose/maltodextrin regulon of Escherichia coli consists of 10 genes which encode a binding proteindependent ABC transporter and four enzymes acting on maltodextrins. All mal genes are controlled by MalT, a transcriptional activator that is exclusively activated by maltotriose. By the action of amylomaltase, we prepared uniformly labeled [ 14 C]maltodextrins from maltose up to maltoheptaose with identical specific radioactivities with respect to their glucosyl residues, which made it possible to quantitatively follow the rate of transport for each maltodextrin. Isogenic malQ mutants lacking maltodextrin phosphorylase (MalP) or maltodextrin glucosidase (MalZ) or both were constructed. The resulting in vivo pattern of maltodextrin metabolism was determined by analyzing accumulated [ 14 C]maltodextrins. MalP ؊ MalZ ؉ strains degraded all dextrins to maltose, whereas MalP ؉ MalZ ؊ strains degraded them to maltotriose. The labeled dextrins were used to measure the rate of transport in the absence of cytoplasmic metabolism. Irrespective of the length of the dextrin, the rates of transport at a submicromolar concentration were similar for the maltodextrins when the rate was calculated per glucosyl residue, suggesting a novel mode for substrate translocation. Strains lacking MalQ and maltose transacetylase were tested for their ability to accumulate maltose. At 1.8 nM external maltose, the ratio of internal to external maltose concentration under equilibrium conditions reached 10 6 to 1 but declined at higher external maltose concentrations. The maximal internal level of maltose at increasing external maltose concentrations was around 100 mM. A strain lacking malQ, malP, and malZ as well as glycogen synthesis and in which maltodextrins are not chemically altered could be induced by external maltose as well as by all other maltodextrins, demonstrating the role of transport per se for induction.

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“…In the absence of inducer, both transcription and translation of malT are limited to a low level because of its poor promoter and the unfavorable ribosome binding site (6). It has been demonstrated that CAP stimulates malT expression by promoting the binding of RNA polymerase to the rather poor promoter (8).…”

Section: Vol 179 1997mentioning

confidence: 99%

Identification and characterization of acoK, a regulatory gene of the Klebsiella pneumoniae acoABCD operon

et al. 1997

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By using transposon insertional mutagenesis and deletion analyses, a recombinant clone containing the region upstream of the acoABCD operon of Klebsiella pneumoniae was found to be required for acetoin-inducible expression of the operon in Escherichia coli. The nucleotide sequence of the region was determined, and it displayed an open reading frame of 2,763 bp that is transcribed divergently to the acoABCD operon. This gene, designated acoK, is capable of encoding a protein with an overall 58.4% amino acid identity with MalT, the transcriptional activator of the E. coli maltose regulon. A conserved sequence for nucleotide binding at the N-terminal region, as well as a helix-turn-helix motif belonging to the LuxR family of transcriptional regulators at the C terminus, was also identified. Primer extension analysis identified two transcription initiation sites, S1 and S2, located 319 and 267 bp, respectively, upstream of the putative start codon of acoK. Several copies of NtrC recognition sequence to N 18 )-GTG] were found in the promoter regions of both the acoK gene and the acoABCD operon. Acetoin-dependent expression of the acoABCD operon could be restored in the E. coli acoK mutants by supplying a plasmid carrying an intact acoK, suggesting a transactivating function of the gene product. The AcoK protein overproduced in E. coli was approximately 100 kDa, which is in good agreement with the molecular mass deduced from the nucleotide sequence. A specific DNA binding property and an ATPase activity of the purified AcoK were also demonstrated.Many bacteria are able to utilize acetoin as a carbon source. In some of the bacteria, dissimilation of acetoin proceeds via an oxidative cleavage process which is catalyzed by an acetoin dehydrogenase enzyme system with acetaldehyde and acetyl coenzyme A as the end products (13, 22). The acetoin dehydrogenase enzyme system is composed of E1␣ and E1␤, an acetoin-dependent dichlorophenolindophenol oxidoreductase (Ao:DCPIP OR); E2, a dihydrolipoamide acetyltransferase; and E3, a dihydrolipoamide dehydrogenase. Structural genes encoding E1␣, E1␤, E2, and E3 of the acetoin dehydrogenase enzyme system have recently been isolated from several bacterial species (11,19,25,28). In Alcaligenes eutrophus, the structural genes identified for E1␣ (acoA), E1␤ (acoB), and E2 (acoC) are clustered with acoX, which encodes a protein of unknown function in the order of acoXABC (28). The structural gene for E3 which is not found in A. eutrophus aco operon, however, is present as acoL in Pelobacter carbinolicus acoABCLS (25) and Clostridium magnum acoABXCL (19) operons and as acoD in the Klebsiella pneumoniae acoABCD operon (27). Amino acid sequences deduced from these genes exhibit significant homology to those of the respective component of various 2-oxo acid dehydrogenase complexes, suggesting an evolutionary relationship among these catabolic systems.Despite the wealth of information on acetoin dehydrogenases, how these aco operons are regulated is less understood. The acoR gene located upst...

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Expression of malT, the regulator gene of the maltose region in Escherichia coli, is limited both at transcription and translation.

Cited by 73 publications

References 25 publications

Intrinsic noise in gene regulatory networks

Intrinsic noise in gene regulatory networks

The Maltodextrin System ofEscherichia coli: Metabolism and Transport

Identification and characterization of acoK, a regulatory gene of the Klebsiella pneumoniae acoABCD operon

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