Phase variation: Genetic analysis of switching mutants

Silverman, Melvin; Simon, Melvin I.

doi:10.1016/0092-8674(80)90075-6

Cited by 177 publications

(124 citation statements)

References 21 publications

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“…50 nt and 25 nt oligonucleotides were included as markers in lanes 1 and 2. C, Bands corresponding to synaptic complexes from reactions employing 36 bp and 50 bp hixL and hixL-AT sites were isolated from native polyacrylamide gels and either incubated with buffer containing 10 mM Mg 2þ prior to extraction in the presence of SDS (þ), or directly extracted in SDS buffer (2 ). The DNA recovered from complexes containing two 50 bp hix sites (50/50), two 36 bp hix sites (36/36), and a 50/36 bp hix hetero-complex was then subjected to denaturing gel electrophoresis (shown).…”

Section: Dna Exchange and Ligationmentioning

confidence: 99%

“…1 -3 The invertible segment contains a promoter that directs the coordinate expression of fljB, a gene encoding the H2 flagellin, and fljA, a gene specifying a repressor of the unlinked H1 flagellin gene, fljC. 2,4 By switching the orientation of the promoter, Hin regulates the alternate expression of the cell-surface antigens H1 and H2, a phenomenon termed flagellar phase variation, which enables the pathogen to temporarily escape a host immune response. 2,5 The invertible segment contains the gene that encodes the 21 kDa (190 amino acid residues) Hin protein as well as a 65 bp recombinational enhancer, which contains two binding sites for the Fis regulatory protein.…”

Section: Introductionmentioning

confidence: 99%

“…2,4 By switching the orientation of the promoter, Hin regulates the alternate expression of the cell-surface antigens H1 and H2, a phenomenon termed flagellar phase variation, which enables the pathogen to temporarily escape a host immune response. 2,5 The invertible segment contains the gene that encodes the 21 kDa (190 amino acid residues) Hin protein as well as a 65 bp recombinational enhancer, which contains two binding sites for the Fis regulatory protein. 6 -10 The cis-acting enhancer is located within the N-terminal region of the hin gene but can function thousands of base-pairs away from and on either side of the recombination sites to stimulate inversion rates by three orders of magnitude.…”

Section: Introductionmentioning

confidence: 99%

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Stepwise Dissection of the Hin-catalyzed Recombination Reaction from Synapsis to Resolution

Johnson

2004

Journal of Molecular Biology

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The Hin DNA invertase promotes a site-specific DNA recombination reaction in the Salmonella chromosome. The native Hin reaction exhibits overwhelming selectivity for promoting inversions between appropriately oriented recombination sites and requires the Fis regulatory protein, a recombinational enhancer, and a supercoiled DNA substrate. Here, we report a robust recombination reaction employing oligonucleotide substrates and a hyperactive mutant form of Hin. Synaptic complex intermediates purified by gel electrophoresis were found to contain four Hin protomers bound to two recombination sites. Each Hin protomer is associated covalently with a cleaved DNA end. The cleaved complexes can be ligated into both parental and recombinant orientations at equivalent frequencies, provided the core residues can base-pair, and are readily disassembled into separated DNA fragments bound by Hin dimers. Kinetic analyses reveal that synapsis occurs rapidly, followed by comparatively slow Hin-catalyzed DNA cleavage. Subsequent steps of the reaction, including DNA exchange and ligation, are fast. Thus, post-synaptic step(s) required for DNA cleavage limit the overall rate of the recombination reaction.

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Section: Dna Exchange and Ligationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stepwise Dissection of the Hin-catalyzed Recombination Reaction from Synapsis to Resolution

Johnson

2004

Journal of Molecular Biology

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“…Gene regulation is sometimes accomplished by DNA rearrangement, as in the cases of mating-type switching in yeast (14) and the expression of variant flagellar antigens in Salmonella species (32), for example. Although we have not found evidence for tissue-specific rearrangement in the case of tRNAsAa genes, the organization of these genes in com-parison with the organization of the constitutive genes is strikingly different.…”

mentioning

confidence: 99%

Silk gland-specific tRNA(Ala) genes are tightly clustered in the silkworm genome.

Underwood¹,

Knickerbocker²,

Gardner³

et al. 1988

Mol. Cell. Biol.

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To understand the basis for tissue-specific production and accumulation of alanine tRNA in silkworms, we have examined the organization of the genes that code for silk gland-specific and constitutive alanine tRNAs. We have found that all of the silk gland-specific tRNAMa genes (-20) appear to be tightly clustered at a single locus in the Bombyx genome. These genes are arranged in tandem at intervals of --150 base pairs. In contrast to the arrangement of the silk gland-specific tRNAAll genes, most of the 20 to 30 constitutive tRNAAIa genes are dispersed in the genome. Silk gland-specific tRNAAla genes are not amplified or grossly rearranged in the silk gland. Thus it is likely that differential transcription, rather than changes in gene number or structure, accounts for the tissue-specific accumulation of tRNAAla.

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“…The H segment is flanked by 26-bp inverted repetitious sequences, hixL and hixR, between which site-specific recombination occurs (Johnson and Simon, 1985). This recombination is mediated by a DNA invertase, Hin, whose gene is located within the H segment (Kutsukake and Iino, 1980;Silverman and Simon, 1980;. The fljB gene constitutes an operon together with the fljA gene, which encodes a negative regulator for fliC expression (Fujita et al, 1973).…”

Section: Introductionmentioning

confidence: 99%

Expressed and cryptic flagellin genes in the H44 and H55 type strains of Escherichia coli

Tominaga

Kutsukake

2007

Genes Genet. Syst.

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Bacterial H antigens are specified by flagellin molecules, which constitute the flagellar filament. Escherichia coli 781-55 and E2987-73 are the type strains for H44 and H55 antigens, respectively. Unlike E. coli K-12, they possess two flagellin genes, fliC and fllA, on their chromosomes. However, they are monophasic, expressing exclusively the fllA genes, which specify the type antigens. In this study, the flagellin genes were cloned from these strains and their structure and expression were analyzed. It was found that the fliC genes encode apparently intact flagellin subunits but possess inefficient σ 28 -dependent promoters, which may result in these genes being silent. The chromosomal locations of the fllA genes are approximately, but not exactly, identical with that of the phase-2 flagellin gene, fljB, of diphasic Salmonella strains. However, unlike the Salmonella fljB gene, the invertible H segment and the fljA gene responsible for the control of flagellar phase variation are both absent from the fllA loci. The fllA genes are highly homologous to the E. coli fliC gene but distantly related to the Salmonella fljB gene. These results suggest a hypothesis that the fllA genes may have emerged by an intra-species lateral transfer of the fliC gene. This hypothesis is further supported by the observation that the fllA genes are flanked by several IS elements and located within cryptic prophage elements.

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Phase variation: Genetic analysis of switching mutants

Cited by 177 publications

References 21 publications

Stepwise Dissection of the Hin-catalyzed Recombination Reaction from Synapsis to Resolution

Stepwise Dissection of the Hin-catalyzed Recombination Reaction from Synapsis to Resolution

Silk gland-specific tRNA(Ala) genes are tightly clustered in the silkworm genome.

Expressed and cryptic flagellin genes in the H44 and H55 type strains of Escherichia coli

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