Degenerated recognition property of a mitochondrial homing enzyme in the unicellular green alga Chlamydomonas smithii

Kurokawa, Sayuri; Yamasaki, Tomohito; Komatsu, Teruaki; Watanabe, Kazuo; Ohama, Takeshi

doi:10.1007/s11103-006-9009-y

Cited by 4 publications

(1 citation statement)

References 39 publications

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“…It has been reported that LHEs can accomplish invasion of intron-deficient alleles with much higher frequency than expected from their measured in vitro cleavage efficiencies, suggesting that a significant amount of mutational deterioration can occur before the persistence and propagation of the endonuclease is irreversibly compromised (33). I-AniI clearly displays many of the suboptimal biophysical and enzymatic properties outlined above, that were reoptimized in the laboratory through the identification of amino-acid substitutions that were selected solely on the basis of improved cleavage activity in bacteria.…”

Section: Discussionmentioning

confidence: 99%

Optimization of in vivo activity of a bifunctional homing endonuclease and maturase reverses evolutionary degradation

Takeuchi

Certo

Caprara

et al. 2008

Nucleic Acids Research

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The LAGLIDADG homing endonuclease (LHE) I-AniI has adopted an extremely efficient secondary RNA splicing activity that is beneficial to its host, balanced against inefficient DNA cleavage. A selection experiment identified point mutations in the enzyme that act synergistically to improve endonuclease activity. The amino-acid substitutions increase target affinity, alter the thermal cleavage profile and significantly increase targeted recombination in transfected cells. The RNA splicing activity is not affected by these mutations. The improvement in DNA cleavage activity is largely focused on one of the enzyme's two active sites, corresponding to a rearrangement of a lysine residue hypothesized to act as a general base. Most of the constructs isolated in the screen contain one or more mutations that revert an amino-acid identity to a residue found in one or more close homologues of I-AniI. This implies that mutations that have previously reduced the endonuclease activity of I-AniI are identified and reversed, sometimes in combination with additional ‘artificial’ mutations, to optimize its in vivo activity.

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Section: Discussionmentioning

confidence: 99%

Optimization of in vivo activity of a bifunctional homing endonuclease and maturase reverses evolutionary degradation

Takeuchi

Certo

Caprara

et al. 2008

Nucleic Acids Research

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Recurrent invasion of mitochondrial group II introns in specimens of Pylaiella littoralis (brown alga), collected worldwide

et al. 2008

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The mitochondrial genome of a filamentous brown alga Pylaiella littoralis (strain CCMP 1907) has been reported to contain four group IIB introns in the LSU rRNA gene and three group IIA introns in the cox1 gene. We found extreme variability in the number of group II introns for these two genes by analyzing eight P. littoralis specimens collected at worldwide habitats. The first intron of the LSU rRNA gene from a specimen collected in France and the fourth intron from a specimen harvested in Japan exhibited an exceptionally long evolutionary distance when compared with the cognate introns found in P. littoralis specimens. Moreover, these introns harbored an intact or nearly intact tripartite ORF, suggesting they are the result of a recent invasion of cognate introns. Based on the fact that many of the target sites were intronless, we propose that opportunity of intron infection is the bottleneck step of the group II intron cycle which consists of invasion, degeneration, and complete loss from the target site.

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The Mitochondrial Genome

Cardol

Remacle

2009

The Chlamydomonas Sourcebook

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Degenerated recognition property of a mitochondrial homing enzyme in the unicellular green alga Chlamydomonas smithii

Cited by 4 publications

References 39 publications

Optimization of in vivo activity of a bifunctional homing endonuclease and maturase reverses evolutionary degradation

Optimization of in vivo activity of a bifunctional homing endonuclease and maturase reverses evolutionary degradation

Recurrent invasion of mitochondrial group II introns in specimens of Pylaiella littoralis (brown alga), collected worldwide

The Mitochondrial Genome

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