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Photoreactivation of Escherichia coli is impaired at high growth temperatures

Paper ID Volume ID Publish Year Pages File Format Full-Text
29731 44432 2015 10 PDF Available
Title
Photoreactivation of Escherichia coli is impaired at high growth temperatures
Abstract

•Photoreactivation of Escherichia coli is impaired at growth temperatures ⩾37 °C.•E. coli photolyase protein levels are decreased at higher growth temperatures.•Steady-state phr transcript levels of E. coli are temperature-independent.•E. coli photolyase is thermal unstable in vitro ⩾37 °C.•Active photolyase but not apo-photolyase is protected in vivo.

Photolyase repairs UV-induced lesions in DNA using light energy, which is the principle of photoreactivation. Active photolyase contains the two-electron-reduced flavin cofactor. We observed that photoreactivation of Escherichia coli was impaired at growth temperatures ⩾37 °C, and growth in this temperature range also resulted in decreased photolyase protein levels in the cells. However, the levels of phr transcripts (encoding photolyase) were almost unchanged at the various growth temperatures. A lacZ-reporter under transcriptional control of the phr promoter showed no temperature-dependent expression. However, a translational reporter consisting of the photolyase N-terminal α/β domain–LacZ fusion protein exhibited lower β-galactosidase activity at high growth temperatures (37–42 °C). These results indicated that the change in photolyase levels at different growth temperatures is post-transcriptional in nature. Limited proteolysis identified several susceptible cleavage sites in E. coli photolyase. In vitro differential scanning calorimetry and activity assays revealed that denaturation of active photolyase occurs at temperatures ⩾37 °C, while apo-photolyase unfolds at temperatures ⩾25 °C. Evidence from temperature-shift experiments also implies that active photolyase is protected from thermal unfolding and proteolysis in vivo, even at 42 °C. These results suggest that thermal unfolding and proteolysis of newly synthesized apo-photolyase, but not active photolyase, is responsible for the impaired photoreactivation at high growth temperatures (37–42 °C).

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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 147, June 2015, Pages 37–46
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
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