Effect of the GC content of DNA on the distribution of UVB-induced bipyrimidine photoproducts

Matallana-Surget, Sabine; Meador, Jarah A.; Joux, Fabien; Douki, Thierry

doi:10.1039/b719929e

Cited by 60 publications

(62 citation statements)

References 58 publications

(44 reference statements)

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“…As members of the phylum Actinobacteria, Streptomyces display a large G‐C content in this genome, mostly above 70% unlike other Gram‐positive bacteria whose G‐C content is usually <50%. It should be kept in mind that the higher the G‐C content, the lower is the amount of total photoproduct, although an increase of photoproduct with cytosine content is observed, which is highly mutagenic compared to the photoproduct TT . These characteristics make their genomes more exposed to photo inducible mutations.…”

Section: Resultsmentioning

confidence: 99%

Photolyases and Cryptochromes in UV‐resistant Bacteria from High‐altitude Andean Lakes

Portero

Alonso-Reyes

Zannier

et al. 2019

Photochem & Photobiology

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“High‐altitude Andean Lakes” (HAAL) are pristine environments harboring poly‐extremophilic microbes that show combined adaptations to physical and chemical stress such as large daily ambient thermal amplitude, extreme solar radiation levels, intense dryness, alkalinity, high concentrations of arsenic (up to 200 ppm) and dissolved salts. In this work, we compared the UV resistance profiles, pigment content and photoreactivation abilities of three UV‐resistant bacteria isolated from distinct niches from HAALs, that is Acinetobacter sp. Ver3 (water, Lake Verde; 4400 m), Exiguobacterium sp. S17 (stromatolite, Lake Socompa, 3570 m) and Nesterenkonia sp. Act20 (soil, Lake Socompa, 3570 m). UV resistance ability of HAAL's strains indicate a clear adaptation to high radiation exposure encountered in their original habitat, which can be explained by genetic and physiological mechanisms named as the UV‐resistome. Thus, the UV‐resistome depends on the expression of a diverse set of genes devoted to evading or repairing the damage it provoked direct or indirectly. As pigment extraction and photoreactive assays indicate the presence of photoactive molecules, we characterized more in detail proteins with homology to photolyases/cryptochromes members (CPF). Phylogenetic analyses, sequence comparison and 3D modeling with bona fide CPF members were used to prove the presence of functional domains and key residues in the novel proteins.

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Section: Resultsmentioning

confidence: 99%

Photolyases and Cryptochromes in UV‐resistant Bacteria from High‐altitude Andean Lakes

Portero

Alonso-Reyes

Zannier

et al. 2019

Photochem & Photobiology

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“…Thus, it is possible that the factors responsible for initiating a high frequency recombination at the flanking regions of MAT locus could also recognize the GC rich intergenic region between the RPO41 and BSP2 genes within the MAT locus, and induce lesions such as double-strand breaks (DSBs) that promote recombination within this region. Additionally, DSBs could also be induced in this region because of the high susceptibility of this region to mutagenic factors due to their high GC content [28]. The DSB could then be repaired through either crossing-over or gene conversion.…”

Section: Discussionmentioning

confidence: 99%

“…However, a recent study of the yeast S. cerevisiae suggests that local GC content is not driven by recombination [21]. Additionally, the local GC content may also influence the susceptibility of a given chromosomal region to mutagenic factors, such as UV radiation [28], and thus indirectly affect the local frequency of recombination required for DNA damage repair processes.…”

Section: Introductionmentioning

confidence: 99%

Gene Conversion Occurs within the Mating-Type Locus of Cryptococcus neoformans during Sexual Reproduction

Sun¹,

Hsueh²,

Heitman

2012

PLoS Genet

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Meiotic recombination of sex chromosomes is thought to be repressed in organisms with heterogametic sex determination (e.g. mammalian X/Y chromosomes), due to extensive divergence and chromosomal rearrangements between the two chromosomes. However, proper segregation of sex chromosomes during meiosis requires crossing-over occurring within the pseudoautosomal regions (PAR). Recent studies reveal that recombination, in the form of gene conversion, is widely distributed within and may have played important roles in the evolution of some chromosomal regions within which recombination was thought to be repressed, such as the centromere cores of maize. Cryptococcus neoformans, a major human pathogenic fungus, has an unusually large mating-type locus (MAT, >100 kb), and the MAT alleles from the two opposite mating-types show extensive nucleotide sequence divergence and chromosomal rearrangements, mirroring characteristics of sex chromosomes. Meiotic recombination was assumed to be repressed within the C. neoformans MAT locus. A previous study identified recombination hot spots flanking the C. neoformans MAT, and these hot spots are associated with high GC content. Here, we investigated a GC-rich intergenic region located within the MAT locus of C. neoformans to establish if this region also exhibits unique recombination behavior during meiosis. Population genetics analysis of natural C. neoformans isolates revealed signals of homogenization spanning this GC-rich intergenic region within different C. neoformans lineages, consistent with a model in which gene conversion of this region during meiosis prevents it from diversifying within each lineage. By analyzing meiotic progeny from laboratory crosses, we found that meiotic recombination (gene conversion) occurs around the GC-rich intergenic region at a frequency equal to or greater than the meiotic recombination frequency observed in other genomic regions. We discuss the implications of these findings with regards to the possible functional and evolutionary importance of gene conversion within the C. neoformans MAT locus and, more generally, in fungi.

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“…UV radiation is one of the most detrimental abiotic factors impacting microorganisms at both community and cellular levels, affecting the microbial diversity and dynamics of community structure, as well as causing damage to important biomolecules such as lipids, DNA and proteins (Matallana-Surget et al, 2008; Matallana-Surget and Wattiez, 2013; Santos et al, 2013; Ayala et al, 2014; Pavlopoulou et al, 2016). Bacteria, especially extremophiles inhabiting harsh environments permanently exposed to damaging solar radiation, have evolved different strategies to cope with UV stress, mainly relying on efficient DNA repair mechanisms and/or active defense against UV-induced oxidative stress, and consequently need to tightly regulate their proteome (Chen et al, 2009; Matallana-Surget et al, 2009, 2014; Gao and Garcia-Pichel, 2011; Albarracín et al, 2012; Matallana-Surget and Wattiez, 2013).…”

Section: Introductionmentioning

confidence: 99%

Bacterial Survival under Extreme UV Radiation: A Comparative Proteomics Study of Rhodobacter sp., Isolated from High Altitude Wetlands in Chile

et al. 2017

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Salar de Huasco, defined as a polyextreme environment, is a high altitude saline wetland in the Chilean Altiplano (3800 m.a.s.l.), permanently exposed to the highest solar radiation doses registered in the world. We present here the first comparative proteomics study of a photoheterotrophic bacterium, Rhodobacter sp., isolated from this remote and hostile habitat. We developed an innovative experimental approach using different sources of radiation (in situ sunlight and UVB lamps), cut-off filters (Mylar, Lee filters) and a high-throughput, label-free quantitative proteomics method to comprehensively analyze the effect of seven spectral bands on protein regulation. A hierarchical cluster analysis of 40 common proteins revealed that all conditions containing the most damaging UVB radiation induced similar pattern of protein regulation compared with UVA and visible light spectral bands. Moreover, it appeared that the cellular adaptation of Rhodobacter sp. to osmotic stress encountered in the hypersaline environment from which it was originally isolated, might further a higher resistance to damaging UV radiation. Indeed, proteins involved in the synthesis and transport of key osmoprotectants, such as glycine betaine and inositol, were found in very high abundance under UV radiation compared to the dark control, suggesting the function of osmolytes as efficient reactive oxygen scavengers. Our study also revealed a RecA-independent response and a tightly regulated network of protein quality control involving proteases and chaperones to selectively degrade misfolded and/or damaged proteins.

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Effect of the GC content of DNA on the distribution of UVB-induced bipyrimidine photoproducts

Cited by 60 publications

References 58 publications

Photolyases and Cryptochromes in UV‐resistant Bacteria from High‐altitude Andean Lakes

Photolyases and Cryptochromes in UV‐resistant Bacteria from High‐altitude Andean Lakes

Gene Conversion Occurs within the Mating-Type Locus of Cryptococcus neoformans during Sexual Reproduction

Bacterial Survival under Extreme UV Radiation: A Comparative Proteomics Study of Rhodobacter sp., Isolated from High Altitude Wetlands in Chile

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