Site-specific restriction endonucleases in cyanobacteria

Lyra, Christina; Halme, Tapio; Torsti, Anna-Maria; Tenkanen, Tuomas; Sivonen, Kaarina

doi:10.1046/j.1365-2672.2000.01206.x

Cited by 13 publications

(8 citation statements)

References 48 publications

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“…Generally, only one or two REases were found in each strain of cyanobacteria through conventional methods to test the crude cell extracts for their restriction activity (29,37). The main reason is the difficulty of detecting Type I RMs or solitary DNA MTases by biochemical or genetic assay (34,41).…”

Section: Discussionmentioning

confidence: 99%

“…The traditional method used to screen for REases is to culture individual strains and test their extracts for the ability to produce specific fragments from small DNA molecules (55). A large number of both filamentous and unicellular cyanobacteria have been shown to contain one or more Type II site-specific REases (29). Lyra et al (29) employed principal component analysis to demonstrate the relationship between certain REases and their hosts and found that all 28 cyanobacterial strains studied contain Type II REases, with the most common cyanobacterial REase types being AvaII, AvaI, and AsuII.…”

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confidence: 99%

“…A large number of both filamentous and unicellular cyanobacteria have been shown to contain one or more Type II site-specific REases (29). Lyra et al (29) employed principal component analysis to demonstrate the relationship between certain REases and their hosts and found that all 28 cyanobacterial strains studied contain Type II REases, with the most common cyanobacterial REase types being AvaII, AvaI, and AsuII. Matveyev et al (31) used experimental and bioinformatics approaches to give a full insight on the MTases of the cyanobacterium Anabaena sp.…”

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Genome-wide analysis of restriction-modification system in unicellular and filamentous cyanobacteria

Zhao

Zhang

Liang

et al. 2006

Physiological Genomics

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. Genome-wide analysis of restrictionmodification system in unicellular and filamentous cyanobacteria. Physiol Genomics 24: 181-190, 2006. First published December 20, 2005 doi:10.1152/physiolgenomics.00255.2005.-Cyanobacteria are an ancient group of gram-negative bacteria with strong genome size variation ranging from 1.6 to 9.1 Mb. Here, we first retrieved all the putative restriction-modification (RM) genes in the draft genome of Spirulina and then performed a range of comparative and bioinformatic analyses on RM genes from unicellular and filamentous cyanobacterial genomes. We have identified 6 gene clusters containing putative Type I RMs and 11 putative Type II RMs or the solitary methyltransferases (MTases). RT-PCR analysis reveals that 6 of 18 MTases are not expressed in Spirulina, whereas one hsdM gene, with a mutated cognate hsdS, was detected to be expressed. Our results indicate that the number of RM genes in filamentous cyanobacteria is significantly higher than in unicellular species, and this expansion of RM systems in filamentous cyanobacteria may be related to their wide range of ecological tolerance. Furthermore, a coevolutionary pattern is found between hsdM and hsdR, with a large number of site pairs positively or negatively correlated, indicating the functional importance of these pairing interactions between their tertiary structures. No evidence for positive selection is found for the majority of RMs, e.g., hsdM, hsdS, hsdR, and Type II restriction endonuclease gene families, while a group of MTases exhibit a remarkable signature of adaptive evolution. Sites and genes identified here to have been under positive selection would provide targets for further research on their structural and functional evaluations.

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Section: Discussionmentioning

confidence: 99%

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Genome-wide analysis of restriction-modification system in unicellular and filamentous cyanobacteria

Zhao

Zhang

Liang

et al. 2006

Physiological Genomics

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“…This has been attributed to its stringent restriction modification system, as well as possible extracellular nucleases that degrade incoming DNA (10,20,42). Although mutants of Tfp genes in M. aerguinosa PCC 7806, including pilT, are currently under investigation to confirm the functionality of its Tfp system, subsequent confirmation of transformability is a substantial hurdle given the low transformation efficiency of M. aeruginosa PCC 7806, as well as its relatively low growth rate (division time, approximately 24 h).…”

Section: Discussionmentioning

confidence: 99%

Functional Analysis of PilT from the Toxic Cyanobacterium Microcystis aeruginosa PCC 7806

et al. 2007

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The evolution of the microcystin toxin gene cluster in phylogenetically distant cyanobacteria has been attributed to recombination, inactivation, and deletion events, although gene transfer may also be involved. Since the microcystin-producing Microcystis aeruginosa PCC 7806 is naturally transformable, we have initiated the characterization of its type IV pilus system, involved in DNA uptake in many bacteria, to provide a physiological focus for the influence of gene transfer in microcystin evolution. The type IV pilus genes pilA, pilB, pilC, and pilT were shown to be expressed in M. aeruginosa PCC 7806. The purified PilT protein yielded a maximal ATPase activity of 37.5 ؎ 1.8 nmol P i min ؊1 mg protein ؊1 , with a requirement for Mg 2؉ . Heterologous expression indicated that it could complement the pilT mutant of Pseudomonas aeruginosa, but not that of the cyanobacterium Synechocystis sp. strain PCC 6803, which was unexpected. Differences in two critical residues between the M. aeruginosa PCC 7806 PilT (7806 PilT) and the Synechocystis sp. strain PCC 6803 PilT proteins affected their theoretical structural models, which may explain the nonfunctionality of 7806 PilT in its cyanobacterial counterpart. Screening of the pilT gene in toxic and nontoxic strains of Microcystis was also performed.

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“…The methylase protects the self DNA from restriction digestion by methylating the nucleotides at specific DNA sequences (i.e., restriction sites), while the foreign DNA, which usually bears a different methylation pattern, would be recognized and degraded by the endonucleases (18). It has been reported that R-M systems can dramatically reduce the DNA transformation efficiency in a variety of bacteria (13,(19)(20)(21)(22)(23)(24), including cyanobacteria (7,(25)(26)(27)(28). For instance, Elhai and coworkers reported that the efficiency of conjugal transfer of shuttle vectors from E. coli into the cyanobacterium Anabaena sp.…”

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Premethylation of Foreign DNA Improves Integrative Transformation Efficiency in Synechocystis sp. Strain PCC 6803

Wang

Zhang

et al. 2015

Appl Environ Microbiol

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cRestriction digestion of foreign DNA is one of the key biological barriers against genetic transformation in microorganisms. To establish a high-efficiency transformation protocol in the model cyanobacterium, Synechocystis sp. strain PCC 6803 (Synechocystis 6803), we investigated the effects of premethylation of foreign DNA on the integrative transformation of this strain. In this study, two type II methyltransferase-encoding genes, i.e., sll0729 (gene M) and slr0214 (gene C), were cloned from the chromosome of Synechocystis 6803 and expressed in Escherichia coli harboring an integration plasmid. After premethylation treatment in E. coli, the integration plasmid was extracted and used for transformation of Synechocystis 6803. The results showed that although expression of methyltransferase M had little impact on the transformation of Synechocystis 6803, expression of methyltransferase C resulted in 11-to 161-fold-higher efficiency in the subsequent integrative transformation of Synechocystis 6803. Effective expression of methyltransferase C, which could be achieved by optimizing the 5= untranslated region, was critical to efficient premethylation of the donor DNA and thus high transformation efficiency in Synechocystis 6803. Since premethylating foreign DNA prior to transforming Synechocystis avoids changing the host genetic background, the study thus provides an improved method for high-efficiency integrative transformation of Synechocystis 6803.

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Site-specific restriction endonucleases in cyanobacteria

Cited by 13 publications

References 48 publications

Genome-wide analysis of restriction-modification system in unicellular and filamentous cyanobacteria

Genome-wide analysis of restriction-modification system in unicellular and filamentous cyanobacteria

Functional Analysis of PilT from the Toxic Cyanobacterium Microcystis aeruginosa PCC 7806

Premethylation of Foreign DNA Improves Integrative Transformation Efficiency in Synechocystis sp. Strain PCC 6803

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