Mechanism of site-specific DNA inversion in bacteria

Johnson, Reid C.

doi:10.1016/s0959-437x(05)80307-7

Cited by 64 publications

(25 citation statements)

References 38 publications

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“…In vitro analysis has shown that Hin-mediated DNA inversion is stimulated over 150-fold in the presence of Fis (26). Together with the recombinational enhancer, Fis is assembled into a synaptic complex with the two Hin-bound recombination sites which is as intermediate required for initiation of DNA strand exchange (24). The lack of any detectable DNA inversion in S. typhimurium fis cells indicates that no other protein functions in this capacity.…”

Section: Discussionmentioning

confidence: 99%

Sequence, regulation, and functions of fis in Salmonella typhimurium

et al. 1995

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The fis operon from Salmonella typhimurium has been cloned and sequenced, and the properties of Fisdeficient and Fis-constitutive strains were examined. The overall fis operon organization in S. typhimurium is the same as that in Escherichia coli, with the deduced Fis amino acid sequences being identical between both species. While the open reading frames upstream of fis have diverged slightly, the promoter regions between the two species are also identical between ؊49 and ؉94. Fis protein and mRNA levels fluctuated dramatically during the course of growth in batch cultures, peaking at ϳ40,000 dimers per cell in early exponential phase, and were undetectable after growth in stationary phase. fis autoregulation was less effective in S. typhimurium than that in E. coli, which can be correlated with the absence or reduced affinity of several Fis-binding sites in the S. typhimurium fis promoter region. Phenotypes of fis mutants include loss of Hin-mediated DNA inversion, cell filamentation, reduced growth rates in rich medium, and increased lag times when the mutants are subcultured after prolonged growth in stationary phase. On the other hand, cells constitutively expressing Fis exhibited normal logarithmic growth but showed a sharp reduction in survival during stationary phase. During the course of these studies, the 28 -dependent promoter within the hin-invertible segment that is responsible for fljB (H2) flagellin synthesis was precisely located.An increasing number of functions are being assigned to the Fis protein (factor for inversion stimulation) in Escherichia coli. Many of these functions have been associated with sitespecific DNA recombination events. Fis was first identified as a factor from E. coli that is required to stimulate site-specific DNA inversion reactions mediated by Salmonella typhimurium Hin (26), by Mu phage Gin (27), and by P1 phage Cin recombinases (20). Fis was also shown to stimulate phage DNA excision and integration (2, 3, 57), which is a mechanistically different DNA recombination reaction (8, 34). Fis also stimulates DNA excision in the case of the -like phage HK022 but, in addition, serves to repress a DNA inversion event upon establishment of lysogeny which would otherwise yield defective lysogens (10). Increased stability of and Mu lysogens is also observed in the presence of Fis (3, 5, 6). Even transposition frequencies of transposon Tn5 and insertion sequence IS50 are found to be influenced by Fis (60).Other functions of Fis are unrelated to specialized DNA recombination and may offer greater competitive advantage to the cell. One such function is its role in stimulating the synthesis of components of the translational machinery. For example, Fis stimulates transcription of rRNA and tRNA genes and genes for proteins involved in translation (19,35,40,51,56). Another role for Fis has been suggested in initiation of chromosomal DNA replication at oriC (12, 16). Cells carrying a fis null mutation show decreased stability of oriC minichromosomes (12, 16) and cannot reinitiate DNA re...

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Section: Discussionmentioning

confidence: 99%

Sequence, regulation, and functions of fis in Salmonella typhimurium

et al. 1995

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“…The latter are present as inverted repeats on a (¹) supercoiled substrate DNA and each site is bound by a single invertase dimer. The architecture of the specific nucleoprotein complex, termed invertasome, which is formed between invertase, Fis, and three DNA segments is very different from that of a synaptosome, and it is mainly this difference that ensures that only inverted sites are efficiently recombined by invertases (Kanaar et al 1990;Heichman & Johnson 1990; reviewed in Johnson & Simon 1987;Johnson 1991).…”

Section: Introductionmentioning

confidence: 99%

The resolvase encoded by Xanthomonas campestris transposable element ISXc5 constitutes a new subfamily closely related to DNA invertases

Liu

Hühne

et al. 1998

Genes to Cells

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Background: Conservative site-specific recombination is responsible for the resolution of cointegrates which result during the transposition of class II transposable elements. Resolution is catalysed by a transposonencoded recombinase, resolvase, that belongs to a large family of recombinases, including DNA invertases. Resolvases and the related invertases are likely to employ similar reaction mechanisms during recombination. There are important differences, however. Resolvases require two accessory DNA binding sites within each of the two directly repeated recombination sites. Invertases instead need a host factor, Fis, and an enhancer type DNA sequence, in addition to two inversely orientated recombination sites.

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“…In the Hin-catalyzed site-specific DNA inversion reaction, the Fis regulatory protein bound to a remote enhancer segment controls the directionality and rate of the reaction (Johnson 1991;van de Putte and Goosen 1992). Fis activates the Hin recombinase only when the protein-bound enhancer and two specific recombination sites have assembled into a topologically correct structure for generating inversion.…”

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confidence: 99%

Communication between Hin recombinase and Fis regulatory subunits during coordinate activation of Hin-catalyzed site-specific DNA inversion

Merickel¹,

Haykinson²,

Johnson³

1998

Genes Dev.

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The Hin DNA invertase becomes catalytically activated when assembled in an invertasome complex containing two Fis dimers bound to an enhancer segment. The region of Fis responsible for transactivation of Hin contains a mobile ␤-hairpin arm that extends from each dimer subunit. We show here that whereas both Fis dimers must be capable of activating Hin, Fis heterodimers that have only one functional activating ␤-arm are sufficient to form catalytically competent invertasomes. Analysis of homodimer and heterodimer mixes of different Hin mutants suggests that Fis must activate each subunit of the two Hin dimers that participate in catalysis. These experiments also indicate that all four Hin subunits must be coordinately activated prior to initiation of the first chemical step of the reaction and that the process of activation is independent of the catalytic steps of recombination. We propose a molecular model for the invertasome structure that is consistent with current information on protein-DNA structures and the topology of the DNA strands within the recombination complex. In this model, a single Fis activation arm could contact amino acids from both Hin subunits at the dimer interface to induce a conformational change that coordinately positions the active sites close to the scissile phosphodiester bonds.

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Mechanism of site-specific DNA inversion in bacteria

Cited by 64 publications

References 38 publications

Sequence, regulation, and functions of fis in Salmonella typhimurium

Sequence, regulation, and functions of fis in Salmonella typhimurium

The resolvase encoded by Xanthomonas campestris transposable element ISXc5 constitutes a new subfamily closely related to DNA invertases

Communication between Hin recombinase and Fis regulatory subunits during coordinate activation of Hin-catalyzed site-specific DNA inversion

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