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The ubiquitin-proteasome pathway protects Chlamydomonas reinhardtii against selenite toxicity, but is impaired as reactive oxygen species accumulate.

Vallentine P, Hung CY, Xie J, Van Hoewyk D - AoB Plants (2014)

Bottom Line: Additionally, proteasomal inhibition decreased the concentration of chlorophyll in cultures challenged with Se.Therefore, although the UPP protects Chlamydomonas against Se stress, severe oxidative stress induced by selenite toxicity likely hinders the UPP's capacity to mediate a stress response.The possibility that stress tolerance in plants is dependent upon optimal UPP activity and maintenance is discussed.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Coastal Carolina University, Conway, SC 29526, USA.

No MeSH data available.


Related in: MedlinePlus

The accumulation of high-molecular-weight ubiquitinated proteins in Chlamydomonas treated with or without selenite at different time points. (A) 50 μg of protein were separated on an 8 % SDS gel and ubiquitinated proteins were detected using anti-ubiquitin antiserum. The immunoblot is representative of two other replicate gels. (B) 20 μg of protein were separated on a 10 % SDS gel and stained with Coomassie to ensure equal loading between lanes. The arrow points to suspected high-molecular-weight ubiquitinated proteins. L, ladder.
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PLU062F2: The accumulation of high-molecular-weight ubiquitinated proteins in Chlamydomonas treated with or without selenite at different time points. (A) 50 μg of protein were separated on an 8 % SDS gel and ubiquitinated proteins were detected using anti-ubiquitin antiserum. The immunoblot is representative of two other replicate gels. (B) 20 μg of protein were separated on a 10 % SDS gel and stained with Coomassie to ensure equal loading between lanes. The arrow points to suspected high-molecular-weight ubiquitinated proteins. L, ladder.

Mentions: As noted above, proteasome activity during Se treatment was both time and dose dependent. We deemed it worthwhile to determine if levels of ubiquitinated proteins were also affected by duration and concentration of Se treatment. During moderate stress induced by 50 μM selenite, high-molecular-weight ubiquitinated proteins were most abundant after 3 and 8 h, but decreased after 28 h of Se-treatment (Fig. 2). Compared with 50 μM selenite, accumulation of ubiquitinated proteins notably declined during severe stress caused by 200 μM selenite after 3 and 8 h, and were absent at 28 h. Coomassie staining of a separate gel confirmed that there was not a significant difference in protein banding between the samples, except for the appearance of high-molecular weight proteins near the top of the gel, presumed to be ubiquitinated proteins (Fig. 2). Together, these data indicate that the accumulation of ubiquitinated proteins induced by selenite is both time and dose dependent, perhaps suggesting that the severity of selenite-induced oxidative stress impairs the ubiquitination of substrate proteins.Figure 2.


The ubiquitin-proteasome pathway protects Chlamydomonas reinhardtii against selenite toxicity, but is impaired as reactive oxygen species accumulate.

Vallentine P, Hung CY, Xie J, Van Hoewyk D - AoB Plants (2014)

The accumulation of high-molecular-weight ubiquitinated proteins in Chlamydomonas treated with or without selenite at different time points. (A) 50 μg of protein were separated on an 8 % SDS gel and ubiquitinated proteins were detected using anti-ubiquitin antiserum. The immunoblot is representative of two other replicate gels. (B) 20 μg of protein were separated on a 10 % SDS gel and stained with Coomassie to ensure equal loading between lanes. The arrow points to suspected high-molecular-weight ubiquitinated proteins. L, ladder.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4231294&req=5

PLU062F2: The accumulation of high-molecular-weight ubiquitinated proteins in Chlamydomonas treated with or without selenite at different time points. (A) 50 μg of protein were separated on an 8 % SDS gel and ubiquitinated proteins were detected using anti-ubiquitin antiserum. The immunoblot is representative of two other replicate gels. (B) 20 μg of protein were separated on a 10 % SDS gel and stained with Coomassie to ensure equal loading between lanes. The arrow points to suspected high-molecular-weight ubiquitinated proteins. L, ladder.
Mentions: As noted above, proteasome activity during Se treatment was both time and dose dependent. We deemed it worthwhile to determine if levels of ubiquitinated proteins were also affected by duration and concentration of Se treatment. During moderate stress induced by 50 μM selenite, high-molecular-weight ubiquitinated proteins were most abundant after 3 and 8 h, but decreased after 28 h of Se-treatment (Fig. 2). Compared with 50 μM selenite, accumulation of ubiquitinated proteins notably declined during severe stress caused by 200 μM selenite after 3 and 8 h, and were absent at 28 h. Coomassie staining of a separate gel confirmed that there was not a significant difference in protein banding between the samples, except for the appearance of high-molecular weight proteins near the top of the gel, presumed to be ubiquitinated proteins (Fig. 2). Together, these data indicate that the accumulation of ubiquitinated proteins induced by selenite is both time and dose dependent, perhaps suggesting that the severity of selenite-induced oxidative stress impairs the ubiquitination of substrate proteins.Figure 2.

Bottom Line: Additionally, proteasomal inhibition decreased the concentration of chlorophyll in cultures challenged with Se.Therefore, although the UPP protects Chlamydomonas against Se stress, severe oxidative stress induced by selenite toxicity likely hinders the UPP's capacity to mediate a stress response.The possibility that stress tolerance in plants is dependent upon optimal UPP activity and maintenance is discussed.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Coastal Carolina University, Conway, SC 29526, USA.

No MeSH data available.


Related in: MedlinePlus