Location of the multivalent control site for the ilvEDA operon of Escherichia coli

Gayda, D J; Leathers, Timothy D.; Noti, John D.; Smith, Frederick M.; Smith, John L.; Subrahmanyam, C S; Umbarger, H. E.

doi:10.1128/jb.142.2.556-567.1980

Cited by 24 publications

(21 citation statements)

References 14 publications

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“…Previous studies from this laboratory had shown that ilv-specific control was exerted on the ilv genes in a plasmid carrying the entire ilv cluster (25). Phages that carried the lac genes fused to ilv DNA that extended through the ilvO region but not through the ilvG region did not exhibit ilv-specific control over 8i-galactosidase (9). However, if the ilvO region was deleted and ilv DNA extending beyond ilvG was included in the ilv-lac fusion phages, ilv-specific control over f8-galactosidase fornation was exhibited.…”

Section: Resultsmentioning

confidence: 89%

“…on July 14, 2020 by guest http://jb.asm.org/ Downloaded from REGULATION OF THE ilvGEDA OPERON 287 to the strong metabolic depression of synthesis of the isoleucineand valine-forming enzymes observed in strains with normal ilv regions (9). Thus, this metabolic depression is not a result of ilv-specific regulation.…”

Section: Resultsmentioning

confidence: 99%

“…144, 1980 that RNA hybridizable to ilvG was forned when the ilvEDA cluster was derepressed (25) and the finding that a phage carrying ilv DNA extending only to the region before ilvE (ilvO) did not exhibit ilv-specific control, whereas one carrying ilv DNA from a region preceding the ilvG gene did exhibit ilv-specific control (9). Furthermore, deletion of the ilvO region did not result in a loss of ilv control over ilvEDA expression but, rather, an enhanced level of ilvEDA expression (9). Thus the possibility was raised that ilvO might be a partially polar mutation that prevented ilvG expression and reduced ilvEDA expression (9).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, deletion of the ilvO region did not result in a loss of ilv control over ilvEDA expression but, rather, an enhanced level of ilvEDA expression (9). Thus the possibility was raised that ilvO might be a partially polar mutation that prevented ilvG expression and reduced ilvEDA expression (9). Thus, ilvO mutations, which led to valine resistance, were viewed as mutations that abolished this polarity and restored ilvG expression.…”

Section: Discussionmentioning

confidence: 99%

“…This idea was further supported by experiments showing that phages with ilv DNA extending through ilvO and into but not through ilvG did not exhibit ilv-specific gene control. In contrast, a phage carrying a deletion of ilvO and flanking portions of ilvE and ilvG but carrying DNA extending beyond ilvG exhibited ilv-specific gene control (9).…”

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confidence: 85%

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Regulation of ilvEDA expression occurs upstream of ilvG in Escherichia coli: additional evidence for an ilvGEDA operon

Subrahmanyam¹,

Noti²,

Umbarger³

1980

J Bacteriol

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A low-copy-number plasmid was prepared that contained the entire ilv gene cluster of Escherichia coli. The introduction of an ilvO mutation allowed the ilvG gene of the plasmid to be expressed and imparted valine resistance to strains carrying it. Insertion of TnlO into the ilvG gene of the plasmid resulted in a strong polar effect on ilv genes E, D, and A. Replacement of a region of ilv deoxyribonucleic acid between two KpnI sites on the high-copy-number plasmid carrying the entire ilv gene cluster with a KpnI fragment carrying an ilv-lac fusion but not extending into the ilv-specific control region resulted in a plasmid expressing the lacZ gene under ilv control when the fusion had been inserted in its normal orientation but not when it had been inserted in the opposite orientation. These experiments indicate that ilv-specific control over ilvE, ilvD, and ilvA expression is dependent on these genes being continguous with deoxyribonucleic acid that lies upstream of ilvG. The results also add further support to the concept of an ilvGEDA operon in E. coli.The ilv gene cluster at 83 min on the Escherichia coli chromosome (Fig. 1) consists of five genes that specify enzymes responsible for isoleucine and valine biosynthesis. Among these, the ilvE, ilvD, and ilvA genes are expressed as a single transcriptional unit (23). The ilvC gene is a separate, inducible transcriptional unit (21). The ilvG gene has been located in this cluster more recently. It is expressed only when there is a mutation in the adjacent ilvO locus (8). The order of these loci has been established to be ilvG, ilvO, ilvEDA, and ilvC (1,18,22,23,25). All of these genes are transcribed in the same direction (4,17,23,25,27). Since ilvG is transcribed in the same direction as ilvEDA, a possibility arises that ilvG might be the first structural gene for an ilvGEDA operon. This idea was further supported by experiments showing that phages with ilv DNA extending through ilvO and into but not through ilvG did not exhibit ilv-specific gene control. In contrast, a phage carrying a deletion of ilvO and flanking portions of ilvE and ilvG but carrying DNA extending beyond ilvG exhibited ilv-specific gene control (9).The one observation contradictory to this idea came from several mutants in which valine-sensitive derivatives had been isolated from ilvO (valine-resistant) strains after Mu-i mutagenesis (cited but not documented in reference 22). The lesions were in ilvG and were presumed to have t Present address:

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 85%

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Regulation of ilvEDA expression occurs upstream of ilvG in Escherichia coli: additional evidence for an ilvGEDA operon

Subrahmanyam¹,

Noti²,

Umbarger³

1980

J Bacteriol

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Identification of the protein products of the rrnC, ilv, rho region of the Escherichia coli K-12 chromosome

1981

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Two methods have been used to identify the protein products of the Escherichia coli K-12 ilv region at 84 min and the flanking rrnC (counterclockwise) and rho (clockwise) loci. First, a set of lambda dilv specialized transducing phages, including some phages that carry rho and others that carry part of rrnC, was used to infect UV irradiated cells. The proteins produced by the infecting lambda dilv phage were selectively labelled with radioactivity amino acids and identified by SDS gel electrophoresis and autoradiography. Second, restriction enzyme fragments were cloned from the lambda dilv phage into pBR322 and the plasmid specific gene products produced in maxicells were similarly identified by SDS gel electrophoresis and autoradiography. The proteins produced were correlated with specific genes and restriction enzyme fragments present in the lambda dilv phage and the pBR322 derivatives. Several ilv gene products that have previously been refractory to protein purification attempts have been identified for the first time by this technique. The presence of mutations at the ilvO site is shown to activate the cryptic ilvG gene and to result in the production of a 62,000 dalton protein. A 15,000 dalton protein of unknown function is synthesized from a DNA segment between ilv and rrnC. The rho gene was cloned from lambda dilv phage into pBR322 and shown to be dominant to a rho mutation on the host chromosome. The rho gene product and four additional proteins coded by genes near or between rho and ilv have been detected.

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The ilvG gene is expressed in Escherichia coli K-12

Berg

Shaw

Berg

1980

Gene

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Location of the multivalent control site for the ilvEDA operon of Escherichia coli

Cited by 24 publications

References 14 publications

Regulation of ilvEDA expression occurs upstream of ilvG in Escherichia coli: additional evidence for an ilvGEDA operon

Regulation of ilvEDA expression occurs upstream of ilvG in Escherichia coli: additional evidence for an ilvGEDA operon

Identification of the protein products of the rrnC, ilv, rho region of the Escherichia coli K-12 chromosome

The ilvG gene is expressed in Escherichia coli K-12

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