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Insights into arsenic multi-operons expression and resistance mechanisms in Rhodopseudomonas palustris CGA009.

Zhao C, Zhang Y, Chan Z, Chen S, Yang S - Front Microbiol (2015)

Bottom Line: Furthermore, ars2 and ars3 operons were maximally transcribed in the early log-phase where ars2 operon was 5.4-fold higher than that of ars3 operon.A low level of ars1 transcript was only detected at 43 h (early log-phase).Arsenic speciation analysis demonstrated that R. palustris could reduce As(V) to As(III).

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering and Biotechnology, Huaqiao University Xiamen, China.

ABSTRACT
Arsenic (As) is widespread in the environment and causes numerous health problems. Rhodopseudomonas palustris has been regarded as a good model organism for studying arsenic detoxification since it was first demonstrated to methylate environmental arsenic by conversion to soluble or gaseous methylated species. However, the detailed arsenic resistance mechanisms remain unknown though there are at least three arsenic-resistance operons (ars1, ars2, and ars3) in R. palustris. In this study, we investigated how arsenic multi-operons contributed to arsenic detoxification in R. palustris. The expression of ars2 or ars3 operons increased with increasing environmental arsenite (As(III)) concentrations (up to 1.0 mM) while transcript of ars1 operon was not detected in the middle log-phase (55 h). ars2 operon was actively expressed even at the low concentration of As(III) (0.01 μM), whereas the ars3 operon was expressed at 1.0 μM of As(III), indicating that there was a differential regulation mechanism for the three arsenic operons. Furthermore, ars2 and ars3 operons were maximally transcribed in the early log-phase where ars2 operon was 5.4-fold higher than that of ars3 operon. A low level of ars1 transcript was only detected at 43 h (early log-phase). Arsenic speciation analysis demonstrated that R. palustris could reduce As(V) to As(III). Collectively, strain CGA009 detoxified arsenic by using arsenic reduction and methylating arsenic mechanism, while the latter might occur with the presence of higher concentrations of arsenic.

No MeSH data available.


Related in: MedlinePlus

Dynamics of expression of ars1, ars2 and ars3 operons. The expression of arsB (black bars), arsC2 (white bars) and arsM (bias bars) was normalized to the expression of gyrB. The growth curve(▴) of R. palustris CGA009 grown on 0.5 mM arsenate is shown as dash line. Error bars indicate the standard deviation from three independent experiments.
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Figure 5: Dynamics of expression of ars1, ars2 and ars3 operons. The expression of arsB (black bars), arsC2 (white bars) and arsM (bias bars) was normalized to the expression of gyrB. The growth curve(▴) of R. palustris CGA009 grown on 0.5 mM arsenate is shown as dash line. Error bars indicate the standard deviation from three independent experiments.

Mentions: The expression dynamics of arsB, arsC2 and arsM (ars1, ars2, and ars3 operons) were investigated in R. palustris CGA009 at different phases of growth (Figure 5). arsC2 expression was highly induced by arsenate at the log-phase (between 43 and 60 h); the expression level decreased when cells entered the stationary phase (67–80 h). A similar expression pattern was found in arsM; however, a relatively low level of expression of arsM was recorded during the whole growth phase, compared to that in arsC2. ars1 transcript level was much lower than those in ars2 and ars3 at different phases of growth.


Insights into arsenic multi-operons expression and resistance mechanisms in Rhodopseudomonas palustris CGA009.

Zhao C, Zhang Y, Chan Z, Chen S, Yang S - Front Microbiol (2015)

Dynamics of expression of ars1, ars2 and ars3 operons. The expression of arsB (black bars), arsC2 (white bars) and arsM (bias bars) was normalized to the expression of gyrB. The growth curve(▴) of R. palustris CGA009 grown on 0.5 mM arsenate is shown as dash line. Error bars indicate the standard deviation from three independent experiments.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585019&req=5

Figure 5: Dynamics of expression of ars1, ars2 and ars3 operons. The expression of arsB (black bars), arsC2 (white bars) and arsM (bias bars) was normalized to the expression of gyrB. The growth curve(▴) of R. palustris CGA009 grown on 0.5 mM arsenate is shown as dash line. Error bars indicate the standard deviation from three independent experiments.
Mentions: The expression dynamics of arsB, arsC2 and arsM (ars1, ars2, and ars3 operons) were investigated in R. palustris CGA009 at different phases of growth (Figure 5). arsC2 expression was highly induced by arsenate at the log-phase (between 43 and 60 h); the expression level decreased when cells entered the stationary phase (67–80 h). A similar expression pattern was found in arsM; however, a relatively low level of expression of arsM was recorded during the whole growth phase, compared to that in arsC2. ars1 transcript level was much lower than those in ars2 and ars3 at different phases of growth.

Bottom Line: Furthermore, ars2 and ars3 operons were maximally transcribed in the early log-phase where ars2 operon was 5.4-fold higher than that of ars3 operon.A low level of ars1 transcript was only detected at 43 h (early log-phase).Arsenic speciation analysis demonstrated that R. palustris could reduce As(V) to As(III).

View Article: PubMed Central - PubMed

Affiliation: Department of Bioengineering and Biotechnology, Huaqiao University Xiamen, China.

ABSTRACT
Arsenic (As) is widespread in the environment and causes numerous health problems. Rhodopseudomonas palustris has been regarded as a good model organism for studying arsenic detoxification since it was first demonstrated to methylate environmental arsenic by conversion to soluble or gaseous methylated species. However, the detailed arsenic resistance mechanisms remain unknown though there are at least three arsenic-resistance operons (ars1, ars2, and ars3) in R. palustris. In this study, we investigated how arsenic multi-operons contributed to arsenic detoxification in R. palustris. The expression of ars2 or ars3 operons increased with increasing environmental arsenite (As(III)) concentrations (up to 1.0 mM) while transcript of ars1 operon was not detected in the middle log-phase (55 h). ars2 operon was actively expressed even at the low concentration of As(III) (0.01 μM), whereas the ars3 operon was expressed at 1.0 μM of As(III), indicating that there was a differential regulation mechanism for the three arsenic operons. Furthermore, ars2 and ars3 operons were maximally transcribed in the early log-phase where ars2 operon was 5.4-fold higher than that of ars3 operon. A low level of ars1 transcript was only detected at 43 h (early log-phase). Arsenic speciation analysis demonstrated that R. palustris could reduce As(V) to As(III). Collectively, strain CGA009 detoxified arsenic by using arsenic reduction and methylating arsenic mechanism, while the latter might occur with the presence of higher concentrations of arsenic.

No MeSH data available.


Related in: MedlinePlus