Effect of araC gene product on catabolite repression in the L-arabinose regulon

Heffernan, L; Wilcox, Gary

doi:10.1128/jb.126.3.1132-1135.1976

Cited by 13 publications

(4 citation statements)

References 8 publications

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“…If the specific (araC activator) and general (CRP) positive control elements have similar functions, or if they act at overlapping sites, a mutation in the activator may be able to bypass the requirement for the cAMP-CRP complex. In the accompanying paper we demonstrate that the mutation has occurred in the araC gene rather than in the araC promoter (22).…”

Section: Resultsmentioning

confidence: 72%

Mutations affecting catabolite repression of the L-arabinose regulon in Escherichia coli B/r

Heffernan¹,

Bass²,

Englesberg³

1976

J Bacteriol

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Expression of the L-arabinose regulon in Escherichia coli B/r requires, among other things, cyclic adenosine-3',5'-monophosphate (cAMP) and the cAMP receptor protein (CRP). Mutants deficient in adenyl cyclase (cya-), the enzyme which synthesizes cAMP, or CRP (crp-) are unable to utilize a variety of carbohydrates, including L-arabinose. Ara+ revertants of a cya-crp-strain were isolated on 0.2% minimal L-arabinose plates, conditions which require the entire ara regulon to be activated in the absence of cAMP and CRP. Evidence from genetic and physiological studies is consistent with placing these mutations in the araC regulatory gene. Deletion mapping with one mutant localized the site within either araO or araC, and complementation tests indicated the mutants acted trans to confer the ability to utilize L-arabinose in a cyacrp-genetic background. Since genetic analysis supports the conclusion that the mutant sites are in the araC regulatory gene, the mutants were designated araCi, indicating a mutation in the regulatory gene affecting the cAMP-CRP requirement. Physiological analysis of one mutant, araC'1, illustrates the transacting nature of the mutation. In a cya-crpgenetic background, araC1l promoted synthesis of both isomerase, a product of the araBAD operon, and permease, a product of the araE operon. Isomerase and permease levels in araCi1 cya+ crp+ were hyperinducible, and the sensitivity of each to cAMP was altered. Two models are presented that show the possible mutational lesion in the araCi strains.

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Section: Resultsmentioning

confidence: 72%

Mutations affecting catabolite repression of the L-arabinose regulon in Escherichia coli B/r

Heffernan¹,

Bass²,

Englesberg³

1976

J Bacteriol

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“…Regulatory proteins were originally classified as activators or repressors if they enhanced or inhibited transcription, respectively. More recent studies, however, indicate that both activators and repressors can exert dual functions, activating or repressing transcription depending on how and where they bind to the DNA (Heffernan & Wilcox, 1976;Aiba, 1983;Choy et al, 1995;Hochschild & Dove, 1998;Schleif, 2000;Lloyd et al, 2001;Scaffidi & Bianchi, 2001;Lim et al, 2003;Browning & Busby, 2004;Yang et al, 2004;van Hijum et al, 2009). Moreover, most transcriptional regulatory systems rely on the function of more than one regulatory protein.…”

Section: Introductionmentioning

confidence: 99%

DNA bending and looping in the transcriptional control of bacteriophage φ29

Camacho

Salas

2010

FEMS Microbiol Rev

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Recent studies on the regulation of phage phi29 gene expression reveal new ways to accomplish the processes required for the orderly gene expression in prokaryotic systems. These studies revealed a novel DNA-binding domain in the phage main transcriptional regulator and the nature and dynamics of the multimeric DNA-protein complex responsible for the switch from early to late gene expression. This review describes the features of the regulatory mechanism that leads to the simultaneous activation and repression of transcription, and discusses it in the context of the role of the topological modification of the DNA carried out by two phage-encoded proteins working synergistically with the DNA.

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“…as well as with DNA sequences within the arab-inose initiator region (1,3,7,8,10,14). The evidence for the interaction of CAP-cAMP with the araC gene protein is based upon the properties of two classes of mutants in the araC gene, both of which exert their mutant phenotypes in trans via the araC protein.…”

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confidence: 99%

“…araCh mutants result in hypersensitivity to catabolite repression, a phenotype that can be partially reversed by addition of cAMP (6,14). araC' mutants, on the other hand, can achieve significant levels of ara operon expression in the absence of CAP-cAMP and are insensitive to catabolite repression (7,8). Mutations in gene araC clearly can alter sensitivity to catabolite repression.…”

mentioning

confidence: 99%

Interaction between mutant alleles of araC of the Escherichia coli B/r L-arabinose operon

Sheppard¹,

Eleuterio²,

Falgout³

1979

J Bacteriol

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Strains were constructed that contain mutational alterations affecting two distinct functional domains within the araC gene protein. The araC' (catabolite repression insensitivity) and araCh (catabolite repression hypersensitivity) mutations were used to alter the catabolite repression sensitivity domain, and mutation to D-fucose resistance was used to alter the inducer binding domain. araCh, D-fucose-resistant double mutants never exhibited constitutive ara operon expression, whereas all of the araC', D-fucose-resistant double mutants did exhibit constitutivity. When L-arabinose was used as an inducer, most of the double mutants exhibited the sensitivity to catabolite repression associated with the araC' or araCh mutation. However, when D-fucose was used as an inducer, changes in sensitivity to catabolite repression were observed that were attributed to interactions between the two protein domains. The roles of catabolite activator protein and araC gene protein in the induction of the araBAD operon were discussed.

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Effect of araC gene product on catabolite repression in the L-arabinose regulon

Abstract: The araCi protein differs in stability from araC+ protein and alters the concentration of cyclic adenosine-3',5'-monophosphate required to maximally stimulate L-arabinose isomerase synthesis in an in vitro protein-synthesizing system.

Cited by 13 publications

References 8 publications

Mutations affecting catabolite repression of the L-arabinose regulon in Escherichia coli B/r

Mutations affecting catabolite repression of the L-arabinose regulon in Escherichia coli B/r

DNA bending and looping in the transcriptional control of bacteriophage φ29

Interaction between mutant alleles of araC of the Escherichia coli B/r L-arabinose operon

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