title: Orchestration of thiamin biosynthesis and central metabolism by combined action of the thiamin pyrophosphate riboswitch and the circadian clock in Arabidopsis.
abstract: Riboswitches are natural RNA elements that posttranscriptionally regulate gene expression by binding small molecules and thereby autonomously control intracellular levels of these metabolites. Although riboswitch-based mechanisms have been examined extensively, the integration of their activity with global physiology and metabolism has been largely overlooked. Here, we explored the regulation of thiamin biosynthesis and the consequences of thiamin pyrophosphate riboswitch deficiency on metabolism in Arabidopsis thaliana. Our results show that thiamin biosynthesis is largely regulated by the circadian clock via the activity of the THIAMIN C SYNTHASE (THIC) promoter, while the riboswitch located at the 3' untranslated region of this gene controls overall thiamin biosynthesis. Surprisingly, the results also indicate that the rate of thiamin biosynthesis directs the activity of thiamin-requiring enzymes and consecutively determines the rate of carbohydrate oxidation via the tricarboxylic acid cycle and pentose-phosphate pathway. Our model suggests that in Arabidopsis, the THIC promoter and the thiamin-pyrophosphate riboswitch act simultaneously to tightly regulate thiamin biosynthesis in a circadian manner and consequently sense and control vital points of core cellular metabolism.
authors: Department of Plant Sciences, Weizman Institute of Science, 76100 Rehovot, Israel.
authors: Samuel E
authors: SE
authors: Bocobza
authors: Sergey
authors: S
authors: Malitsky
authors: Wagner L
authors: WL
authors: Araújo
authors: Adriano
authors: A
authors: Nunes-Nesi
authors: Sagit
authors: S
authors: Meir
authors: Michal
authors: M
authors: Shapira
authors: Alisdair R
authors: AR
authors: Fernie
authors: Asaph
authors: A
authors: Aharoni
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050260:Carbohydrate Metabolism; D057906:Circadian Clocks / Q000235:genetics*; D002952:Citric Acid Cycle / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007506:Iron-Sulfur Proteins / Q000235:genetics* / Q000378:metabolism; D008027:Light; D008954:Models, Biological; D009154:Mutation; D010084:Oxidation-Reduction; D010427:Pentose Phosphate Pathway / Q000235:genetics; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D058928:Riboswitch / Q000235:genetics*; D013831:Thiamine / Q000032:analysis / Q000096:biosynthesis; D013835:Thiamine Pyrophosphate / Q000235:genetics / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D029681:Arabidopsis Proteins; D007506:Iron-Sulfur Proteins; D018749:RNA, Plant; D058928:Riboswitch; C525883:THIC protein, Arabidopsis; D013835:Thiamine Pyrophosphate; D013831:Thiamine