Growth phase and ompR regulation of transcription of microcin B17 genes

Hernández-Chico, C; Millán, José L. San; Kolter, Roberto; Moreno, Felipe

doi:10.1128/jb.167.3.1058-1065.1986

Cited by 61 publications

(57 citation statements)

References 42 publications

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“…Production of both MccB17 and MccC7 is growth phase dependent. However, MccB17 production is OmpR dependent (28), while MccC7 production is AppR dependent (16). proU induction is triggered by osmotic up-shock, but it is growth phase independent and does not depend on OmpR (36).…”

Section: Discussionmentioning

confidence: 99%

“…Microcin B17 (MccB17) is a bactericidal peptide of about 3,200 Da which inhibits DNA replication, induces the SOS repair system, and finally causes DNA degradation (15,30). Both microcins are plasmid encoded and are produced when cultures cease exponential growth and enter the stationary phase (19,28). Thus, microcins constitute a good model system for investigating the molecular mechanisms regulating gene expression in nongrowing cells.…”

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confidence: 99%

“…Three promoters have been identified in this region (24, 28). The major promoter from which all the genes are transcribed is a growth phase-regulated OmpRdependent promoter located upstream of mcbA (11,28).…”

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confidence: 99%

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mprA, an Escherichia coli gene that reduces growth-phase-dependent synthesis of microcins B17 and C7 and blocks osmoinduction of proU when cloned on a high-copy-number plasmid

1990

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Microcins B17 and C7 are plasmid-determined, peptide antibiotics produced by Escherichia coli when cells enter the stationary phase of growth. Microcinogenic strains are immune to the action of the microcin they synthesize. A well-characterized deficient-immunity phenotype is exhibited by microcin B17-producing cells in the absence of the immunity gene mcbG (M.C. Garrido, M. Herrero, R. Kolter, and F. Moreno, EMBO J. 7:1853-1862, 1988). A 14.6-kilobase-pair EcoRI chromosomal fragment was isolated by its ability to suppress this phenotype when cloned into a multicopy vector. This fragment was mapped to 57.5 min on the E. coli genetic map. The position of the gene responsible for suppression, designated mprA, was determined by insertional mutagenesis and deletion analysis. mprA was shown to be transcribed clockwise on the E. coli chromosome, and its product was identified as a 19-kilodalton polypeptide. Suppression was shown to be achieved by decreasing microcin B17 production. Increased mprA gene dosage also caused a decrease in microcin C7 production and blocked the osmoinduction of the proU locus in high-osmolarity media. Our results suggest that the mprA gene product could play a regulatory role on expression of several E. coli genes, this control being exerted at the transcriptional level.

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Section: Discussionmentioning

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mprA, an Escherichia coli gene that reduces growth-phase-dependent synthesis of microcins B17 and C7 and blocks osmoinduction of proU when cloned on a high-copy-number plasmid

1990

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“…Downstream of mcbA are mcbBCDEFG, whose products are responsible for posttranslational modification of McbA, microcin B17 export, and immunity and resistance to microcin B17 (20,39,40). MprA, a negative regulator of microcin B17 gene expression (7), PmbA, purported to be involved in leader processing (25), and OmpR, a positive regulator of microcin B17, ompC, and ompF gene expression (14,24), are all chromosomally encoded. Similarly, we have found a gene, tfuA, that lies outside of the tfx gene cluster and is involved in TFX production.…”

Section: Discussionmentioning

confidence: 99%

A newly discovered gene, tfuA, involved in the production of the ribosomally synthesized peptide antibiotic trifolitoxin

1996

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Trifolitoxin (TFX) is a gene-encoded, posttranslationally modified peptide antibiotic. Previously, we have shown that tfxABCDEFG from Rhizobium leguminosarum bv. trifolii T24 is sufficient to confer TFX production and resistance to nonproducing strains within a distinct taxonomic group of the ␣-proteobacteria (E. W. Triplett, B. T. Breil, and G. A. Splitter, Appl. Environ. Microbiol. 60:4163-4166, 1994). Here we describe strain Tn5-2, a Tn5 mutant of T24 defective in the production of TFX, whose insertion maps outside of the tfx cluster. It is not altered in growth compared with T24, nor does it inactivate TFX in its proximity. The wild-type analog of the mutated region of Tn5-2 was cloned. Sequencing, transcriptional fusion mutagenesis, and subcloning were used to identify tfuA, a gene involved in TFX production. On the basis of computer analysis, the putative TfuA protein has a mass of 72.9 kDa and includes a peroxidase motif but no transmembrane domains. TFX production studies show that extra copies of the tfxABCDEFG fragment increase TFX production in a T24 background while additional copies of tfuA do not. Lysate ribonuclease protection assays suggest that tfuA does not regulate transcription of tfxA. Upstream of tfuA are two open reading frames (ORFs). The putative product of ORF1 shows high similarity to the LysR family of transcriptional regulators. The putative product of ORF2 shows high similarity to the cytosine deaminase (CodA) of Escherichia coli.Trifolitoxin (TFX) is a ribosomally synthesized, posttranslationally modified peptide antibiotic produced by Rhizobium leguminosarum bv. trifolii T24 (4, 29). A number of features make TFX an interesting antibiotic for study. Its spectrum of activity is quite narrow but includes bacteria that are plant symbionts and plant and animal pathogens (29,34,35). TFX has already been shown to limit nodules formed by TFXsensitive strains (32-34) and so may provide a solution to the Rhizobium competition problem (9, 36). This problem arises when inoculant strains are not competitive for legume root nodulation against strains indigenous to soil. Its ribosomal synthesis makes it an easy substrate for drug modification (12,16,17,27). Though the structure of TFX has not been completely elucidated, it is known to contain a thiazoline ring and another cyclic chromophore (23). The latter appears to be a novel, pyrimidine-like structure (unpublished results). It may be possible to use the enzymes that modify TFX to modify different substrates, thereby creating new molecules. EpiD from the epidermin system has been used to catalyze the oxidative decarboxylation of heptapeptides (21), thereby showing the very real possibility of using antibiotic posttranslational modification enzymes to catalyze reactions on molecules other than their natural preantibiotic target. Given the TFX system's agricultural, medical, and biochemical potential, elucidation of the genetics of TFX production is important.A number of genes have been shown to be required for TFX production and resistance. T...

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“…This fragment includes six genes (mcbABCDEF) responsible for MccB17 synthesis and secretion and one gene (mcbG) responsible for immunity to the antibiotic (10,12). All of these genes are transcribed from a growth-phase-regulated OmpR-dependent promoter located upstream of mcbA (Pmcb) (2,12,14).…”

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Nucleotide sequence of the Escherichia coli regulatory gene mprA and construction and characterization of mprA-deficient mutants

et al. 1991

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In high copy number, the Escherichia coli mprA gene reduces the synthesis of peptide microcins B17 and C7 (MccB17 and MccC7) and blocks the osmoinduction of the proU operon at the transcriptional level. mprA has been sequenced and shown to encode a polypeptide of 176 amino acids (Mr,20,563). Insertion and deletion mutant mprA alleles were constructed and then transferred to the chromosome by allelic replacement. In these mutants, expression of two mcb-lacZ fusions was fivefold derepressed, indicating a negative regulatory role of mprA on the mcb operon (MccB17). In contrast, no effect of the MprA-mutations on the expression of mcc operon (MccC7) or on the osmoinduction of proU operon was observed.

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Growth phase and ompR regulation of transcription of microcin B17 genes

Cited by 61 publications

References 42 publications

mprA, an Escherichia coli gene that reduces growth-phase-dependent synthesis of microcins B17 and C7 and blocks osmoinduction of proU when cloned on a high-copy-number plasmid

mprA, an Escherichia coli gene that reduces growth-phase-dependent synthesis of microcins B17 and C7 and blocks osmoinduction of proU when cloned on a high-copy-number plasmid

A newly discovered gene, tfuA, involved in the production of the ribosomally synthesized peptide antibiotic trifolitoxin

Nucleotide sequence of the Escherichia coli regulatory gene mprA and construction and characterization of mprA-deficient mutants

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