Photoreactivation in an archaeon from geothermal environments

Grogan, Dennis W.

doi:10.1099/00221287-143-4-1071

Cited by 15 publications

(16 citation statements)

References 17 publications

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“…Although the magnitude of the effects, and thus their reversal, was modest at low fluences, at high fluence (where survival, reversion, and recombinogenic responses were all approximately exponential with dose), photoreactivation attenuated all three effects by similar factors (13ϫ, 15ϫ, and 15ϫ, respectively) ( Table 3). The inability of photoreactivation to completely reverse the effects of high fluence (e.g., 70 J/m 2 ) is consistent with prior indications that photoreactivation can repair only about 80% of the lethal UV damage to S. acidocaldarius cells under these conditions (8).…”

Section: Fig 2 Formation Of Phenotypic Revertants the Number Of Pyrsupporting

confidence: 72%

“…In some experiments, duplicate samples of UV-irradiated cells were withdrawn at the appropriate times; one sample was processed normally (i.e., under dim red light), whereas the duplicate (in a colorless polypropylene microcentrifuge tube) was illuminated for 2 h at about 13 W/m 2 in a foil-lined tray by a bank of fluorescent lamps. According to a previous study, this dose of visible light gives the maximal photoreactivation possible under these conditions, corresponding to a reversal of about 80% of the lethal lesions induced by UV (8).…”

Section: Methodsmentioning

confidence: 99%

“…This device emits 70% of its light output at wavelengths shorter than about 300 nm, yielding a short-wavelength UV intensity of 3.5 W/m 2 at the surface of the cell suspension (8). Unless otherwise noted, all UV fluences (i.e., doses) refer to this short-wavelength (Ͻ300-nm) component of the lamp output.…”

Section: Methodsmentioning

confidence: 99%

“…S. acidocaldarius is efficiently photoreactivated at 24°C or higher temperatures following UV irradiation, which suggests specific photoenzymatic repair of pyrimidine dimers in the S. acidocaldarius chromosome (8). We therefore investigated the ability of subsequent illumination by visible light to reverse the genetic effects of UV in S. acidocaldarius cells.…”

Section: Fig 2 Formation Of Phenotypic Revertants the Number Of Pyrmentioning

confidence: 99%

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Genetic responses of the thermophilic archaeon Sulfolobus acidocaldarius to short-wavelength UV light

1997

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The archaea which populate geothermal environments are adapted to conditions that should greatly destabilize the primary structure of DNA, yet the basic biological aspects of DNA damage and repair remain unexplored for this group of prokaryotes. We used auxotrophic mutants of the extremely thermoacidophilic archaeon Sulfolobus acidocaldarius to assess genetic and physiological effects of a well-characterized DNAdamaging agent, short-wavelength UV light. Simple genetic assays enabled quantitative dose-response relationships to be determined and correlated for survival, phenotypic reversion, and the formation of genetic recombinants. Dose-response relationships were also determined for survival and phenotypic reversion of the corresponding Escherichia coli auxotrophs with the same equipment and procedures. The results showed S. acidocaldarius to be about twice as UV sensitive as E. coli and to be equally UV mutable on a surviving-cell basis. Furthermore, UV irradiation significantly increased the frequency of recombinants recovered from geneticexchange assays of S. acidocaldarius. The observed UV effects were due to the short-wavelength (i.e., UV-C) portion of the spectrum and were effectively reversed by subsequent illumination of S. acidocaldarius cells with visible light (photoreactivation). Thus, the observed responses are probably initiated by the formation of pyrimidine dimers in the S. acidocaldarius chromosome. To our knowledge, these results provide the first evidence of error-prone DNA repair and genetic recombination induced by DNA damage in an archaeon from geothermal habitats.

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Section: Fig 2 Formation Of Phenotypic Revertants the Number Of Pyrsupporting

confidence: 72%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Fig 2 Formation Of Phenotypic Revertants the Number Of Pyrmentioning

confidence: 99%

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Genetic responses of the thermophilic archaeon Sulfolobus acidocaldarius to short-wavelength UV light

1997

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“…Among thermophilic archaea, the greatest number of genetic processes occur in members of the genus Sulfolobus ; for example, spontaneous mutation (Jacobs & Grogan, 1997), UV-induced mutation (Wood et al, 1997) and photoreactivation (Grogan, 1997) have been studied in Sulfolobus acidocaldarius. Moreover, S. acidocaldarius spontaneously exchanges and recombines chromosomal genetic markers (Grogan, 1996a).…”

Section: Introductionmentioning

confidence: 99%

Chromosomal marker exchange in the thermophilic archaeon Sulfolobus acidocaldarius: physiological and cellular aspects

Ghane

Grogan

1998

Microbiology

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Exchange and recombination of chromosomal markers is an intrinsic genetic property of the thermoacidophilic archaeon Sulfolobus acidocaldarius that has not been thoroughly characterized. T o clarify the mechanism and experimental usefulness of this process, the frequency of 5. acidocaldarius prototrophs produced from mixtures of two pyrimidine auxotrophs under a variety of conditions was determined. The apparent efficiency of genetic exchange was essentially independent of the density of cells deposited on the surface of solid media. Furthermore, recombinant formation could initiate in liquid suspensions, as indieated by high recombinant frequencies resulting from mixtures plated at low cell densities, and the formation of recombinants a t equal or higher frequencies in liquid suspensions that were never plated. Apparent initiation of genetic exchange in liquid a t 22 "C was not prevented by DNase, prior digestion of parental cells with protease from Streptomyces griseus, or any other non-lethal chemical agent tested. The results support prior indications that chromosomal marker exchange in S. acidocaldarius proceeds via conjugation, and further indicate that this conjugation can initiate quickly in dilute liquid suspension. The mating system of S. acidocaldarius thus appears physiologically distinct from that of Haloferax volcanii but perhaps similar to conjugational transfer of Sulfolobus plasmid pNOB8. The frequency of recombinants formed in these assays (10'4-10'5 per c.f.u.) greatly exceeds the number of spontaneous forward mutational events per generation for biosynthetic genes in S. acidocaldarius. This suggests that chromosomal exchange has the potential to influence the genetic dynamics of natural Sulfolobus populations.

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Early Evolution of DNA Repair Mechanisms

DiRuggiero

Robb

2004

The Genetic Code and the Origin of Life

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DNA repair is critical for the maintenance of genome integrity and replication fidelity in all cells, and therefore was arguably of major importance in the Last Universal Cellular Ancestor (LUCA) as well. Archaea, and hyperthermophiles in particular, are well suited for studying early DNA repair mechanisms from two perspeaives. First, these prokaryotes embody a mix of bacterial and eukaryal molecular features. Second, DNA in many archaea is subject to ongoing damage during normal growth under extreme conditions such as high temperature or low pH. Third, recent work suggests that the mutation rates of model hyperthermophiles are quite close to norms for bacteria, indicating that their replication/repair processes are operating with high fidelity at elevated temperatures. The Archaea also have minimal sets of genes involved in all of the major cellular information transfer processes, compared with Eukarya, which have highly paralogous and redundant sets of genes for DNA replication, repair and recombination.Repair activities have been demonstrated for several hyperthermophiles including our studies with Pyrococcus furiosus, an archaeon growing optimally at 100°C. In addition, using comparative genomic analysis and the genome sequence of several hyperthermophilic archaea, homologs of conserved eukaryotic and bacterial DNA repair proteins have been identified. Although close to 100 microbial genome sequences have been analyzed, including 16 from the Archaea, so far many highly conserved repair genes are missing in some or in all of the archaeal genomes. This may be the result of low sequence conservation across the three domains of life, preventing identification using sequence similarity searches. It is possible, and proven in some instances, that Archaea have novel versions of repair proteins.Here we argue that the commonality of mechanisms and protein sequences, shared between prokaryotes and eukaryotes for several modes of DNA repair, reflects diversification from a minimal set of genes. However, for several pathways, the close similarity between components of eukaryal and archaeal repair pathways suggests that those specific processes likely evolved independendy in the bacterial and archaeal/eukaryal lineages.

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Photoreactivation in an archaeon from geothermal environments

Cited by 15 publications

References 17 publications

Genetic responses of the thermophilic archaeon Sulfolobus acidocaldarius to short-wavelength UV light

Genetic responses of the thermophilic archaeon Sulfolobus acidocaldarius to short-wavelength UV light

Chromosomal marker exchange in the thermophilic archaeon Sulfolobus acidocaldarius: physiological and cellular aspects

Early Evolution of DNA Repair Mechanisms

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