Diversity of restriction–modification gene homologues in Helicobacter pylori

Nobusato, Ayaka; Uchiyama, Ikuo; Kobayashi, Ichizo

doi:10.1016/s0378-1119(00)00455-8

Cited by 71 publications

(58 citation statements)

References 31 publications

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“…Analyses of various bacterial genomes provided evidence that RM gene systems can move between bacterial genomes, which seems to be consistent with their behavior as selfish DNA elements (21,23,31,35,36). Their association with genome rearrangements was inferred from comparisons of closely related bacterial genomes (2,36) and was demonstrated experimentally (15).…”

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confidence: 63%

Stability of EcoRI Restriction-Modification Enzymes In Vivo Differentiates the EcoRI Restriction-Modification System from Other Postsegregational Cell Killing Systems

Ichige

Kobayashi

2005

J Bacteriol

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Certain type II restriction modification gene systems can kill host cells when these gene systems are eliminated from the host cells. Such ability to cause postsegregational killing of host cells is the feature of bacterial addiction modules, each of which consists of toxin and antitoxin genes. With these addiction modules, the differential stability of toxin and antitoxin molecules in cells plays an essential role in the execution of postsegregational killing. We here examined in vivo stability of the EcoRI restriction enzyme (toxin) and modification enzyme (antitoxin), the gene system of which has previously been shown to cause postsegregational host killing in Escherichia coli. Using two different methods, namely, quantitative Western blot analysis and pulse-chase immunoprecipitation analysis, we demonstrated that both the EcoRI restriction enzyme and modification enzyme are as stable as bulk cellular proteins and that there is no marked difference in their stability. The numbers of EcoRI restriction and modification enzyme molecules present in a host cell during the steady-state growth were estimated. We monitored changes in cellular levels of the EcoRI restriction and modification enzymes during the postsegregational killing. Results from these analyses together suggest that the EcoRI gene system does not rely on differential stability between the toxin and the antitoxin molecules for execution of postsegregational cell killing. Our results provide insights into the mechanism of postsegregational killing by restriction-modification systems, which seems to be distinct from mechanisms of postsegregational killing by other bacterial addiction modules.

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confidence: 63%

Stability of EcoRI Restriction-Modification Enzymes In Vivo Differentiates the EcoRI Restriction-Modification System from Other Postsegregational Cell Killing Systems

Ichige

Kobayashi

2005

J Bacteriol

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“…Comparative analyses of the genomes of H. pylori strains predicted the presence of a large number of putative R-M systems but with a high degree of heterogeneity (196,197). Further analyses revealed that only some of these systems retain enzyme activity (195,198).…”

Section: R-m Systems Of Helicobacter Pylorimentioning

confidence: 98%

Diverse Functions of Restriction-Modification Systems in Addition to Cellular Defense

Vasu

Nagaraja

2013

Microbiol Mol Biol Rev

509

462

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SUMMARY Restriction-modification (R-M) systems are ubiquitous and are often considered primitive immune systems in bacteria. Their diversity and prevalence across the prokaryotic kingdom are an indication of their success as a defense mechanism against invading genomes. However, their cellular defense function does not adequately explain the basis for their immaculate specificity in sequence recognition and nonuniform distribution, ranging from none to too many, in diverse species. The present review deals with new developments which provide insights into the roles of these enzymes in other aspects of cellular function. In this review, emphasis is placed on novel hypotheses and various findings that have not yet been dealt with in a critical review. Emerging studies indicate their role in various cellular processes other than host defense, virulence, and even controlling the rate of evolution of the organism. We also discuss how R-M systems could have successfully evolved and be involved in additional cellular portfolios, thereby increasing the relative fitness of their hosts in the population.

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“…Their horizontal transfer between distant groups of bacteria has been suggested by sequence comparison (Malone et al, 1995) and by analysis of their codon usage and GC content (Nobusato et al, 2000a). For instance, RM genes were found in a region of the H. pylori genome that is characterized by the presence of strain-specific genes and translocation events forming the so-called plasticity zone (Alm et al, 1999;Salama et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

Restriction-modification systems in Mycoplasma spp

2007

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Restriction and Modification (R-M) systems are present in all Mycoplasma species sequenced so far. The presence of these genes poses barriers to gene transfer and could protect the cell against phage infections. The number and types of R-M genes between different Mycoplasma species are variable, which is characteristic of a polymorphism. The majority of the CDSs code for Type III R-M systems and particularly for methyltransferase enzymes, which suggests that functions other than the protection against the invasion of heterologous DNA may exist. A possible function of these enzymes could be the protection against the invasion of other but similar R-M systems. In Mycoplasma hyopneumoniae strain J, three of the putative methyltransferase genes were clustered in a region forming a genomic island. Many R-M CDSs were mapped in the vicinity of transposable elements suggesting an association between these genes and reinforcing the idea of R-M systems as mobile selfish DNA. Also, many R-M genes present repeats within their coding sequences, indicating that their expression is under the control of phase variation mechanisms. Altogether, these data suggest that R-M systems are a remarkable characteristic of Mycoplasma species and are probably involved in the adaptation of these bacteria to different environmental conditions.

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Diversity of restriction–modification gene homologues in Helicobacter pylori

Cited by 71 publications

References 31 publications

Stability of EcoRI Restriction-Modification Enzymes In Vivo Differentiates the EcoRI Restriction-Modification System from Other Postsegregational Cell Killing Systems

Stability of EcoRI Restriction-Modification Enzymes In Vivo Differentiates the EcoRI Restriction-Modification System from Other Postsegregational Cell Killing Systems

Diverse Functions of Restriction-Modification Systems in Addition to Cellular Defense

Restriction-modification systems in Mycoplasma spp

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