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Deficiencies in RNS2‐mediated ribosomal RNA turnover cause changes in the Pentose Phosphate Pathway flux and alter cell growth in Arabidopsis
Author(s) -
MacIntosh Gustavo C,
Morriss Stephanie,
Liu Xiaoyi,
Bassham Diane
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.911.3
Subject(s) - pentose phosphate pathway , arabidopsis , biology , ribosomal rna , mutant , transcriptome , biochemistry , microbiology and biotechnology , arabidopsis thaliana , ribosome biogenesis , rna , ribosome , gene , gene expression , metabolism , glycolysis
Enzymes belonging to the RNase T2 family are essential for normal ribosomal RNA turnover in eukaryotes. In Arabidopsis thaliana this function is performed by RNS2. The null mutant rns2‐2 has increased rRNA half‐life and constitutive autophagy. To determine the effect of defective rRNA turnover on cellular homeostasis, we used comparative transcriptome and metabolome analyses of 10 day old wild‐type and rns2‐2 seedlings to identify molecular processes affected in the mutant. Bioinformatics analyses suggested additional phenotypes that were confirmed through direct plant size measurements and microscopy. Few genes were differentially expressed in the rns2‐2 mutant, indicating that control of autophagy in this genotype is mainly achieved at the posttranscriptional level. Among differentially expressed genes we identified transcripts related to carbon flux processes, particularly the pentose phosphate pathway, and metabolite analyses confirmed changes in the levels of PPP intermediates. We also found differentially expressed genes related to cell wall loosening and found a decrease in monosaccharide components of cell wall hemicellulose. As a potential effect of weaker cell walls, rns2‐2 plants are larger than wild‐type controls, due to larger cells and increased water content. We propose that lack of rRNA recycling in rns2‐2 cells triggers a change in carbon flux, which is redirected through the pentose phosphate pathway to produce ribose‐5‐P for de novo nucleoside synthesis. rRNA or ribosome turnover is thus essential to maintain nucleoside homeostasis in Arabidopsis. Support or Funding Information This work was supported by a grant from the United States National Science Foundation [MCB‐1051818] to G.C.M. and D.C.B.