Affiliation:
1. Department of Cell and Molecular Biology, Lundberg Laboratory, Göteborg University, S-405 30 Göteborg, Sweden
2. Department of Genetics and Microbiology, Charles University, 116 34 Prague 1, Czech Republic
Abstract
Rck2 is a mitogen-activated protein kinase-activated protein kinase in yeast implicated in translational regulation. rck2Δ mutants are mildly sensitive to oxidative stress, a condition that causes dissociation of actively translating ribosomes (polysomes). In rck2Δ cells, polysomes are lost to an even higher degree than in the wild-type upon stress. Cells overexpressing the catalytically inactive rck2-kd allele are highly sensitive to oxidative stress. In such cells, dissociation of polysomes upon stress was instead greatly delayed. The protein synthesis rate decreased to a similar degree as in wild-type cells, however, indicating that in rck2-kd cells, the polysome complexes were inactive. Array analyses of total and polysome-associated mRNAs revealed major deregulation of the translational machinery in rck2 mutant cells. This involves transcripts for cytosolic ribosomal proteins and for processing and assembly of ribosomes. In rck2Δ cells, weakly transcribed mRNAs associate more avidly with polysomes than in wild-type cells, whereas the opposite holds true for rck2-kd cells. This is consistent with perturbed regulation of translation elongation, which is predicted to alter the ratio between mRNAs with and without strong entry sites at ribosomes. We infer that imbalances in the translational apparatus are a major reason for the inability of these cells to respond to stress.
Publisher
American Society for Cell Biology (ASCB)
Subject
Cell Biology,Molecular Biology
Cited by
41 articles.
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