Analysis of Chlamydomonas thiamin metabolism in vivo reveals riboswitch plasticity
| Autor: | Michael Moulin, Alison G. Smith, Thérésa Bridget Fitzpatrick, Ginnie T. D. T. Nguyen, Mark A. Scaife |
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| Rok vydání: | 2013 |
| Předmět: |
0106 biological sciences
Riboswitch Thiamine Pyrophosphate/chemistry/metabolism Chlamydomonas reinhardtii 01 natural sciences Phosphotransferases (Phosphate Group Acceptor)/genetics/metabolism chemistry.chemical_compound Gene Expression Regulation Plant Thiamine Riboswitch/genetics Plant Proteins Biosynthetic Pathways/genetics 0303 health sciences Multidisciplinary biology Molecular Structure Reverse Transcriptase Polymerase Chain Reaction food and beverages Biological Sciences Algal Proteins/genetics/metabolism ddc:580 Biochemistry Pyrimidine metabolism Thiamine pyrophosphate Protein Binding 03 medical and health sciences Point Mutation Pyrimidines/biosynthesis/chemistry 030304 developmental biology Phosphotransferases (Phosphate Group Acceptor) Alternative splicing Chlamydomonas Algal Proteins Plant biology.organism_classification Biosynthetic Pathways Alternative Splicing Thiazoles Pyrimidines Gene Expression Regulation chemistry Thiamine/chemistry/metabolism Thiazoles/chemistry/metabolism Thiamine Pyrophosphate Plant Proteins/genetics/metabolism human activities Function (biology) Chlamydomonas reinhardtii/genetics/metabolism 010606 plant biology & botany |
| Zdroj: | Proceedings of the National Academy of Sciences, Vol. 110, No 36 (2013) pp. 14622-14627 |
| ISSN: | 1091-6490 0027-8424 |
| Popis: | Thiamin (vitamin B 1 ) is an essential micronutrient needed as a cofactor for many central metabolic enzymes. Animals must have thiamin in their diet, whereas bacteria, fungi, and plants can biosynthesize it de novo from the condensation of a thiazole and a pyrimidine moiety. Although the routes to biosynthesize these two heterocycles are not conserved in different organisms, in all cases exogenous thiamin represses expression of one or more of the biosynthetic pathway genes. One important mechanism for this control is via thiamin-pyrophosphate (TPP) riboswitches, regions of the mRNA to which TPP can bind directly, thus facilitating fine-tuning to maintain homeostasis. However, there is little information on how modulation of riboswitches affects thiamin metabolism in vivo. Here we use the green alga, Chlamydomonas reinhardtii , which regulates both thiazole and pyrimidine biosynthesis with riboswitches in the THI4 (Thiamin 4) and THIC (Thiamin C) genes, respectively, to investigate this question. Our study reveals that regulation of thiamin metabolism is not the simple dogma of negative feedback control. Specifically, balancing the provision of both of the heterocycles of TPP appears to be an important requirement. Furthermore, we show that the Chlamydomonas THIC riboswitch is controlled by hydroxymethylpyrimidine pyrophosphate, as well as TPP, but with an identical alternative splicing mechanism. Similarly, the THI4 gene is responsive to thiazole. The study not only provides insight into the plasticity of the TPP riboswitches but also shows that their maintenance is likely to be a consequence of evolutionary need as a function of the organisms’ environment and the particular pathway used. |
| Databáze: | OpenAIRE |
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