Mechanism of action of Salmonella phage P22 antirepressor

Susskind, Miriam M.; Botstein, David

doi:10.1016/s0022-2836(75)80127-6

Cited by 101 publications

(52 citation statements)

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“…RHH family members are present in bacteria, archaea, and bacteriophages (16). These proteins display diverse regulatory functions, such as bacteriophage gene regulation (17), plasmid maintenance and segregation (18,19), plasmid antitoxin and repressor functions (20), and metabolite-dependent (21) and metal-dependent (13,22) gene regulation.…”

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Helicobacter pylori NikR Protein Exhibits Distinct Conformations When Bound to Different Promoters

Benanti¹,

Chivers

2011

Journal of Biological Chemistry

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Helicobacter pylori requires nickel ions as cofactors for the urease and hydrogenase enzymes, which are important for the colonization of animal models of infection (1-3). This virulence requirement has motivated numerous studies of nickel-dependent gene regulation in H. pylori. The Ni 2ϩ -responsive transcription factor NikR from H. pylori (HpNikR) 3 regulates the expression of multiple genes by directly binding to their promoters in response to increasing nickel (4 -10). HpNikR is an exquisitely sensitive nickel sensor with a K D,Ni of ϳ2 pM (4, 5); however, how that affinity translates to gene regulation in cells remains unclear (e.g. in rich media, changes in gene expression are observed in response to ϳ100 M) (6, 9 -11). From these studies, it appears that the recognition sequences in each promoter are defined by a series of poorly conserved 6-bp imperfect inverted repeat half-sites separated by a 15-bp spacer (5,7,12). HpNikR binds to these promoters with a range of affinities (5, 12). The promiscuity of DNA binding by HpNikR contrasts with high sequence selectivity of the NikR proteins from Escherichia coli (EcNikR (13, 14)) and Geobacter uraniireducens (GuNikR (15)), which recognize highly conserved inverted repeats found in only one or two promoter regions per genome. The NikR protein family represents an excellent system with which to understand the role of protein and DNA sequence in the expansion of prokaryotic regulatory networks.NikR proteins are ribbon-helix-helix (RHH) transcription factors. RHH family members are present in bacteria, archaea, and bacteriophages (16). These proteins display diverse regulatory functions, such as bacteriophage gene regulation (17), plasmid maintenance and segregation (18,19), plasmid antitoxin and repressor functions (20), and metabolite-dependent (21) and metal-dependent (13, 22) gene regulation.The archetypical RHH fold (ϳ45-50 amino acids) consists of a single ␤-strand followed by two ␣-helices, with the two ␤-strands of each obligate RHH dimer forming an antiparallel ␤-sheet motif (23). Structural studies of the Arc and MetJ repressors first demonstrated that the RHH ␤-sheet motif sits in the major groove of DNA, with three solvent-exposed residues making base-specific hydrogen bonds via their side chains (23)(24)(25). Nonspecific DNA phosphate contacts were also observed in the structures, some by tandem turn regions N-terminal to the ␤-sheets and others by the N terminus of helix ␣2 of the RHH domain (23-25). These protein-phosphate interactions are hypothesized to attach the N terminus and helix ␣2 to the DNA backbone and link these structural elements to the ␤-sheet (23). The helix ␣2-phosphate backbone interactions are shared among all of the RHH protein-DNA co-crystal structures (16, 24 -30

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Helicobacter pylori NikR Protein Exhibits Distinct Conformations When Bound to Different Promoters

Benanti¹,

Chivers

2011

Journal of Biological Chemistry

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“…A possible but unlikely model for GAL4-GAL80 protein interaction in the regulation of the galactose-meli- biose genes js that the GAL80 protein is a repressor which binds a DNA operator site of the target genes, and in the presence of inducer, the GAL4 protein acts as a simple antirepressor analogous to the P22 antirepressor (31). Genetic attempts to isolate GAL4-independent gal80 constitutive mutants (gal4 gal80 galactose fermenters), expected at a high frequency on the basis of an antirepressor model, have not yielded such mutants in gal4 strains (<10-'(') (26).…”

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Disruption of regulatory gene GAL80 in Saccharomyces cerevisiae: effects on carbon-controlled regulation of the galactose/melibiose pathway genes.

Torchia¹,

Hamilton²,

Cano³

et al. 1984

Mol. Cell. Biol.

141

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In Saccharomyces cerevisiae, the transcriptional expression of the galactose-melibiose catabolic pathway genes is under the control of at least three regulatory genes, GAL4, GAL80, and GAL3. We have isolated the GAL80 gene and have studied the effect of a null mutation on the carbon-controlled regulation of the MEL] and GAL cluster genes. The null mutation was achieved in vivo by replacing the chromosomal wild-type GAL80 allele with an in vitro-created GAL80 deletion-disruption mutation. Enzyme activities and RNA levels for the GAL cluster and MEL] genes were constitutively expressed in the null mutant strain grown on glycerol-lactate and were higher than in the isogenic wild-type yeast strain when compared after growth on galactose. Carbon catabolite repression of the GAL cluster and MEL] genes, which occurs at the level of transcription, is retained in the null mutant. Deletion of the GAL80 gene in a gal4 cell does not restore GAL cluster and MEL) gene expression. The data demonstrate that (i) the GAL80 protein is a purely negative regulator, (ii) the GAL80 protein does not mediate carbon catabolite repression, and (iii) the GAL4 protein is not simply an antagonizer of GAL80-mediated repression.At least three genetically defined regulatory genes (GAL4, GAL80, and GAL3) control the galactose-inducible expression of five structural genes which code for enzymes required for galactose or melibiose catabolism. The appearance of the enzyme activities specified by the MELI (axgalactosidase), GAL2 (galactose permease), and the tightly linked GAL cluster genes, GAL] (galactokinase), GAL7 (Gal-i-P uridyl transferase), and GALIO (UDPG-4-epimerase) is coordinately controlled (3,4,7,16). These structural genes comprise separate transcriptional units (13, 30). Considerable genetic evidence indicates that the GAL4 and GAL80 regulatory genes function via diffusable proteins (8,17,20,21) to activate or inactivate coordinately the transcription of the structural genes (12,27,30).The GAL4 protein has been assigned a positive regulatory function based on genetic data (6). The GAL3 function is necessary for normal rapid induction; gal3 mutants exhibit slower induction and a prolonged induction lag (33) which occurs at transcription (T. E. Torchia and J. E. Hopper, manuscript in preparation).The GAL80 protein is thought to be necessary to prevent structural gene expression in the absence of galactose, as suggested by the constitutive phenotype of cells with recessive gal80 mutations and the noninducible phenotype of cells with dominant GAL80S mutations (6,8,25 tein may be multifunctional with some required role in gene expression. Although cells bearing a recessive gal80 nonsense mutation are constitutive, it is not known whether this mutation occurs early or late in the protein sequence (8). Defined deletion mutations in GAL80, which could be used to resolve the role of the GAL80 protein, have not been studied.In addition to galactose control, this system is repressed by glucose (1). The role of the regulatory proteins in glucose ...

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“…Colonies of this strain remain fluorescent on plates containing ethidium bromide after toluene treatment (C. Colson, personal communication). Strain ~~5 5 7 5 was obtained after mutagenesis by ethyl methanesulphonate and screening with methyl green (Susskind & Botstein, 1975). Both strains are therefore assumed to lack a major endonuclease activity.…”

Section: Resultsmentioning

confidence: 99%

A Salmonella typhimurium Endonuclease that Converts Native DNA to Fragments of about 8 X 105 daltons

Schumann

Bade

1977

Journal of General Microbiology

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319Crude extracts of Salmonella typhimurium were found to contain an endonuclease that degraded double-stranded linear DNA from bacteria and phages to fragments with a molecular weight of about 8 x 105. The nuclease did not have an absolute requirement for Mg2+. One discrete intermediate product had a molecular weight of 6.6 x I O~. Extracts from two different mutants were tested : one completely lacked the endonuclease activity (strain DB5575), and the other showed an absolute requirement for Mg2+ (strain 4543). No biological role has yet been found for this endonuclease of S. typhimurium.

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Mechanism of action of Salmonella phage P22 antirepressor

Cited by 101 publications

References 22 publications

Helicobacter pylori NikR Protein Exhibits Distinct Conformations When Bound to Different Promoters

Helicobacter pylori NikR Protein Exhibits Distinct Conformations When Bound to Different Promoters

Disruption of regulatory gene GAL80 in Saccharomyces cerevisiae: effects on carbon-controlled regulation of the galactose/melibiose pathway genes.

A Salmonella typhimurium Endonuclease that Converts Native DNA to Fragments of about 8 X 105 daltons

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