Genomic Responses to Arsenic in the Cyanobacterium Synechocystis sp. PCC 6803

Sánchez-Riego, Ana María; López‐Maury, Luis; Florencio, Francisco J.

doi:10.1371/journal.pone.0096826

Cited by 37 publications

(24 citation statements)

References 96 publications

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“…The transcription of sll0914 is regulated by ArsR (arsenic-resistance regulatory protein); however, its role in arsenic resistance was not clear (Sánchez-Riego et al 2014). Sll0914 resulted in an R180G mutant in our adapted cells.…”

Section: Whole-genome Sequencing Analysis Of the Adapted Strainsmentioning

confidence: 91%

Genomic analysis of parallel-evolved cyanobacterium Synechocystis sp. PCC 6803 under acid stress

et al. 2015

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Experimental evolution is a powerful tool for clarifying phenotypic and genotypic changes responsible for adaptive evolution. In this study, we isolated acid-adapted Synechocystis sp. PCC 6803 (Synechocystis 6803) strains to identify genes involved in acid tolerance. Synechocystis 6803 is rarely found in habitants with pH < 5.75. The parent (P) strain was cultured in BG-11 at pH 6.0. We gradually lowered the pH of the medium from pH 6.0 to pH 5.5 over 3 months. Our adapted cells could grow in acid stress conditions at pH 5.5, whereas the parent cells could not. We performed whole-genome sequencing and compared the acid-adapted and P strains, thereby identifying 11 SNPs in the acid-adapted strains, including in Fo F1-ATPase. To determine whether the SNP genes responded to acid stress, we examined gene expression in the adapted strains using quantitative reverse-transcription polymerase chain reaction. sll0914, sll1496, sll0528, and sll1144 expressions increased under acid stress in the P strain, whereas sll0162, sll0163, slr0623, and slr0529 expressions decreased. There were no differences in the SNP genes expression levels between the P strain and two adapted strains, except for sll0528. These results suggest that SNPs in certain genes are involved in acid stress tolerance in Synechocystis 6803.

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Section: Whole-genome Sequencing Analysis Of the Adapted Strainsmentioning

confidence: 91%

Genomic analysis of parallel-evolved cyanobacterium Synechocystis sp. PCC 6803 under acid stress

et al. 2015

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“…In cyanobacteria, morphological, physiological and biochemical changes, genomics, and proteomics have been found to be involved in response to arsenic stress (Srivastava et al, 2009; Pandey et al, 2012; Sánchez-Riego et al, 2014). Furthermore, various cyanobacteria were shown to be able to accumulate and resist arsenic by multiple arsenic biotransformations (Yin et al, 2012; Wang et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Co-expression of Cyanobacterial Genes for Arsenic Methylation and Demethylation in Escherichia coli Offers Insights into Arsenic Resistance

et al. 2017

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Arsenite [As(III)] and methylarsenite [MAs(III)] are the most toxic inorganic and methylated arsenicals, respectively. As(III) and MAs(III) can be interconverted in the unicellular cyanobacterium Nostoc sp. PCC 7120 (Nostoc), which has both the arsM gene (NsarsM), which is responsible for arsenic methylation, and the arsI gene (NsarsI), which is responsible for MAs(III) demethylation. It is not clear how the cells prevent a futile cycle of methylation and demethylation. To investigate the relationship between arsenic methylation and demethylation, we constructed strains of Escherichia coli AW3110 (ΔarsRBC) expressing NsarsM or/and NsarsI. Expression of NsarsI conferred MAs(III) resistance through MAs(III) demethylation. Compared to NsArsI, NsArsM conferred higher resistance to As(III) and lower resistance to MAs(III) by methylating both As(III) and MAs(III). The major species found in solution was dimethylarsenate [DMAs(V)]. Co-expression of NsarsM and NsarsI conferred As(III) resistance at levels similar to that with NsarsM alone, although the main species found in solution after As(III) biotransformation was methylarsenate [MAs(V)] rather than DMAs(V). Co-expression of NsarsM and NsarsI conferred a higher level of resistance to MAs(III) than found with expression of NsarsM alone but lower than expression of only NsarsI. Cells co-expressing both genes converted MAs(III) to a mixture of As(III) and DMAs(V). In Nostoc NsarsM is constitutively expressed, while NsarsI is inducible by either As(III) or MAs(III). Thus, our results suggest that at low concentrations of arsenic, NsArsM activity predominates, while NsArsI activity predominates at high concentrations. We propose that coexistence of arsM and arsI genes in Nostoc could be advantageous for several reasons. First, it confers a broader spectrum of resistance to both As(III) and MAs(III). Second, at low concentrations of arsenic, the MAs(III) produced by NsArsM will possibly have antibiotic-like properties and give the organism a competitive advantage. Finally, these results shed light on the role of cyanobacteria in the arsenic biogeochemical cycle.

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“…Studies using an arsR knock-out mutant in other organisms like Synechocystis sp. PCC 6803 have shown that those mutants seem to be hypersensitive to metals like Ni 2+ , Cu 2+ and Cd 2+(Sanchez-Riego et al 2014).…”

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confidence: 99%