Global translational responses to oxidative stress impact upon multiple levels of protein synthesis.
Global inhibition of protein synthesis is a common response to stress conditions. We have analyzed the regulation of protein synthesis in response to oxidative stress induced by exposure to H(2)O(2) in the yeast Saccharomyces cerevisiae. Our data show that H(2)O(2) causes an inhibition of translation initiation dependent on the Gcn2 protein kinase, which phosphorylates the alpha-subunit of eukaryotic initiation factor-2. Additionally, our data indicate that translation is regulated in a Gcn2-independent manner because protein synthesis was still inhibited in response to H(2)O(2) in a gcn2 mutant. Polysome analysis indicated that H(2)O(2) causes a slower rate of ribosomal runoff, consistent with an inhibitory effect on translation elongation or termination. Furthermore, analysis of ribosomal transit times indicated that oxidative stress increases the average mRNA transit time, confirming a post-initiation inhibition of translation. Using microarray analysis of polysome- and monosome-associated mRNA pools, we demonstrate that certain mRNAs, including mRNAs encoding stress protective molecules, increase in association with ribosomes following H(2)O(2) stress. For some candidate mRNAs, we show that a low concentration of H(2)O(2) results in increased protein production. In contrast, a high concentration of H(2)O(2) promotes polyribosome association but does not necessarily lead to increased protein production. We suggest that these mRNAs may represent an mRNA store that could become rapidly activated following relief of the stress condition. In summary, oxidative stress elicits complex translational reprogramming that is fundamental for adaptation to the stress.
Shenton
Daniel
D
Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom.
Smirnova
Julia B
JB
Selley
Julian N
JN
Carroll
Kathleen
K
Hubbard
Simon J
SJ
Pavitt
Graham D
GD
Ashe
Mark P
MP
Grant
Chris M
CM
D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D010766:Phosphorylation; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*
D015852:Eukaryotic Initiation Factor-2; D012333:RNA, Messenger; D006861:Hydrogen Peroxide